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docs/tutorials/javascript/amm/add-assets-to-amm.md
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# Add Assets to an AMM
Follow the steps from the [Create an AMM](/docs/tutorials/javascript/amm/create-an-amm/) tutorial before proceeding.
This example shows how to:
1. Deposit assets to an existing [AMM](/docs/concepts/tokens/decentralized-exchange/automated-market-makers) and receive LP tokens.
2. Vote on AMM trading fees.
3. Check the value of your LP tokens.
4. Redeem LP tokens for assets in the AMM pair.
[![Add assets to AMM test harness](/docs/img/quickstart-add-to-amm1.png)](/docs/img/quickstart-add-to-amm1.png)
You can download the [Quickstart Samples](https://github.com/XRPLF/xrpl-dev-portal/tree/master/_code-samples/quickstart/js/) archive to try each of the samples in your own browser.
{% admonition type="info" name="Note" %}
Without the Quickstart Samples, you will not be able to try the examples that follow.
{% /admonition %}
## Usage
### Get Accounts
1. Open `12.add-to-amm.html` in a browser.
2. Select **Testnet** or **Devnet**
3. Get test accounts.
- If you have existing account seeds:
1. Paste account seeds in the **Seeds** field.
2. Click **Get Accounts from Seeds**.
- If you don't have account seeds:
1. Click **Get New Standby Account**.
2. Click **Get New Operational Account**.
[![Get account results](/docs/img/quickstart-add-to-amm2.png)](/docs/img/quickstart-add-to-amm2.png)
### Get the AMM
Use the information from either the XRP/Token or Token/Token AMM you created in [Create an AMM](/docs/tutorials/javascript/amm/create-an-amm/#create-an-xrp/token-amm).
1. Enter a [currency code](/docs/references/protocol/data-types/currency-formats.md#currency-codes) in the **Asset 1 Currency** field. For example, `XRP`.
2. Enter a second currency code in the **Asset 2 Currency** field. For example, `TST`.
3. Enter the operational account address in the **Asset 2 Issuer** field.
4. Click **Check AMM**.
[![Get AMM results](/docs/img/quickstart-add-to-amm3.png)](/docs/img/quickstart-add-to-amm3.png)
### Deposit a Single Asset to the AMM
You can deposit either asset, but depositing only one asset reduces the amount of LP tokens you receive.
1. Click **Get Balances** to verify how many tokens you have.
2. Enter a value in the **Asset 1 Amount** field.
3. Click **Add to AMM**.
[![Add assets to AMM results](/docs/img/quickstart-add-to-amm4.png)](/docs/img/quickstart-add-to-amm4.png)
### Deposit Both Assets to the AMM
1. Click **Get Balances** to verify how many tokens you have.
2. Enter a value in the **Asset 1 Amount** field.
3. Enter a value in the **Asset 2 Amount** field.
4. Click **Add to AMM**.
[![Add assets to AMM results](/docs/img/quickstart-add-to-amm5.png)](/docs/img/quickstart-add-to-amm5.png)
### Vote on trading fees
1. Enter a value in the **Trading Fee** field. The proposed fee is in units of 1/100,000; a value of 1 is equivalent to 0.001%. The maximum value is 1000, indicating a 1% fee.
2. Click **Vote on Fee**.
[![Vote on trading fees results](/docs/img/quickstart-add-to-amm6.png)](/docs/img/quickstart-add-to-amm6.png)
### Redeem Your LP Tokens
1. Click **Get LP Value**.
2. Enter a value in the **LP Tokens** field.
3. Click **Redeem LP**.
[![Get LP token value results](/docs/img/quickstart-add-to-amm7.png)](/docs/img/quickstart-add-to-amm7.png)
## Code Walkthrough
You can open `ripplex12-add-to-amm.js` from the [Quickstart Samples](https://github.com/XRPLF/xrpl-dev-portal/tree/master/_code-samples/quickstart/js/) to view the source code.
### Add Assets to an Existing AMM
This code checks if you're trying to add one or both assets, and then modifies the `AMMDeposit` transaction to be either a single or double-asset deposit.
```javascript
async function addAssets() {
```
Connect to the XRP Ledger.
```javascript
let net = getNet()
const client = new xrpl.Client(net)
results = `\n\nConnecting to ${getNet()} ...`
standbyResultField.value = results
await client.connect()
results += '\n\nConnected.'
standbyResultField.value = results
```
Get the AMM information fields.
```javascript
const standby_wallet = xrpl.Wallet.fromSeed(standbySeedField.value)
const asset1_currency = asset1CurrencyField.value
const asset1_issuer = asset1IssuerField.value
const asset1_amount = asset1AmountField.value
const asset2_currency = asset2CurrencyField.value
const asset2_issuer = asset2IssuerField.value
const asset2_amount = asset2AmountField.value
```
Format the `AMMDeposit` transaction based on the combination of `XRP` and tokens.
```javascript
// Check for all combinations of asset deposits.
let ammdeposit = null
if (asset1_currency == "XRP" && asset2_currency && asset1_amount && asset2_amount ) {
ammdeposit = {
"TransactionType": "AMMDeposit",
"Asset": {
currency: "XRP"
},
"Asset2": {
currency: asset2_currency,
issuer: asset2_issuer
},
"Account": standby_wallet.address,
"Amount": xrpl.xrpToDrops(asset1_amount),
"Amount2": {
currency: asset2_currency,
issuer: asset2_issuer,
value: asset2_amount
},
"Flags": 0x00100000
}
} else if ( asset1_currency && asset2_currency == "XRP" && asset1_amount && asset2_amount ) {
ammdeposit = {
"TransactionType": "AMMDeposit",
"Asset": {
currency: asset1_currency,
issuer: asset1_issuer
},
"Asset2": {
currency: "XRP"
},
"Account": standby_wallet.address,
"Amount": {
currency: asset1_currency,
issuer: asset1_issuer,
value: asset1_amount
},
"Amount2": xrpl.xrpToDrops(asset2_amount),
"Flags": 0x00100000
}
} else if ( asset1_currency && asset2_currency && asset1_amount && asset2_amount ) {
ammdeposit = {
"TransactionType": "AMMDeposit",
"Asset": {
currency: asset1_currency,
issuer: asset1_issuer
},
"Asset2": {
currency: asset2_currency,
issuer: asset2_issuer
},
"Account": standby_wallet.address,
"Amount": {
currency: asset1_currency,
issuer: asset1_issuer,
value: asset1_amount
},
"Amount2": {
currency: asset2_currency,
issuer: asset2_issuer,
value: asset2_amount
},
"Flags": 0x00100000
}
} else if ( asset1_currency == "XRP" && asset2_currency && asset1_amount ) {
ammdeposit = {
"TransactionType": "AMMDeposit",
"Asset": {
currency: "XRP"
},
"Asset2": {
currency: asset2_currency,
issuer: asset2_issuer
},
"Account": standby_wallet.address,
"Amount": xrpl.xrpToDrops(asset1_amount),
"Flags": 0x00080000
}
} else if ( asset1_currency && asset2_currency == "XRP" && asset1_amount ) {
ammdeposit = {
"TransactionType": "AMMDeposit",
"Asset": {
currency: asset1_currency,
issuer: asset1_issuer
},
"Asset2": {
currency: "XRP"
},
"Account": standby_wallet.address,
"Amount": {
currency: asset1_currency,
issuer: asset1_issuer,
value: asset1_amount
},
"Flags": 0x00080000
}
} else if ( asset1_currency == "XRP" && asset2_currency && asset2_amount ) {
ammdeposit = {
"TransactionType": "AMMDeposit",
"Asset": {
currency: "XRP"
},
"Asset2": {
currency: asset2_currency,
issuer: asset2_issuer
},
"Account": standby_wallet.address,
"Amount": {
currency: asset2_currency,
issuer: asset2_issuer,
value: asset2_amount
},
"Flags": 0x00080000
}
} else if ( asset1_currency && asset2_currency && asset1_amount ) {
ammdeposit = {
"TransactionType": "AMMDeposit",
"Asset": {
currency: asset1_currency,
issuer: asset1_issuer
},
"Asset2": {
currency: asset2_currency,
issuer: asset2_issuer
},
"Account": standby_wallet.address,
"Amount": {
currency: asset1_currency,
issuer: asset1_issuer,
value: asset1_amount
},
"Flags": 0x00080000
}
} else if ( asset1_currency && asset2_currency && asset2_amount ) {
ammdeposit = {
"TransactionType": "AMMDeposit",
"Asset": {
currency: asset1_currency,
issuer: asset1_issuer
},
"Asset2": {
currency: asset2_currency,
issuer: asset2_issuer
},
"Account": standby_wallet.address,
"Amount": {
currency: asset2_currency,
issuer: asset2_issuer,
value: asset2_amount
},
"Flags": 0x00080000
}
} else {
results += `\n\nNo assets selected to add ...`
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
return
}
```
Prepare the transaction for submission. Wrap the submission in a `try-catch` block to handle any errors.
```javascript
try {
const prepared_deposit = await client.autofill(ammdeposit)
results += `\n\nPrepared transaction:\n${JSON.stringify(prepared_deposit, null, 2)}`
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
```
Sign the transaction using the standby account wallet.
```javascript
const signed_deposit = standby_wallet.sign(prepared_deposit)
results += `\n\nSending AMMDeposit transaction ...`
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
```
Submit the signed transaction to the XRPL. Run the `checkAMM()` function to update the AMM's information in the AMM log on a successful transaction.
```javascript
const lp_deposit = await client.submitAndWait(signed_deposit.tx_blob)
if (lp_deposit.result.meta.TransactionResult == "tesSUCCESS") {
results += `\n\nTransaction succeeded.`
checkAMM()
} else {
results += `\n\nError sending transaction: ${JSON.stringify(lp_deposit.result.meta.TransactionResult, null, 2)}`
}
} catch (error) {
results += `\n\n${error.message}`
}
```
Report the transaction results in the standby account log.
```javascript
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
client.disconnect()
}
```
### Vote on Trading Fees
Trading fees are applied to any transaction that interacts with the AMM. As with the `addAssets()` function, this one checks the combination of assets provided to modifty the `ammVote` transaction.
```javascript
async function voteFees() {
```
Connect to the XRP Ledger.
```javascript
let net = getNet()
const client = new xrpl.Client(net)
results = `\n\nConnecting to ${getNet()} ...`
standbyResultField.value = results
await client.connect()
results += '\n\nConnected.'
standbyResultField.value = results
```
Get the AMM information and vote fee fields.
```javascript
const standby_wallet = xrpl.Wallet.fromSeed(standbySeedField.value)
const voteFee = standbyFeeField.value
const asset1_currency = asset1CurrencyField.value
const asset1_issuer = asset1IssuerField.value
const asset2_currency = asset2CurrencyField.value
const asset2_issuer = asset2IssuerField.value
```
Format the `AMMVote` transaction based on the combination of `XRP` and tokens.
```javascript
let ammvote = null
if ( asset1_currency == "XRP" ) {
ammvote = {
"TransactionType": "AMMVote",
"Asset": {
"currency": "XRP"
},
"Asset2": {
"currency": asset2_currency,
"issuer": asset2_issuer
},
"Account": standby_wallet.address,
"TradingFee": Number(voteFee)
}
} else if ( asset2_currency == "XRP" ) {
ammvote = {
"TransactionType": "AMMVote",
"Asset": {
"currency": asset1_currency,
"issuer": asset1_issuer
},
"Asset2": {
"currency": "XRP"
},
"Account": standby_wallet.address,
"TradingFee": Number(voteFee)
}
} else {
ammvote = {
"TransactionType": "AMMVote",
"Asset": {
"currency": asset1_currency,
"issuer": asset1_issuer
},
"Asset2": {
"currency": asset2_currency,
"issuer": asset2_issuer
},
"Account": standby_wallet.address,
"TradingFee": Number(voteFee)
}
}
```
Prepare the transaction for submission. Wrap the submission in a `try-catch` block to handle any errors.
```javascript
try {
const prepared_vote = await client.autofill(ammvote)
results += `\n\nPrepared transaction:\n${JSON.stringify(prepared_vote, null, 2)}`
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
```
Sign the prepared transaction using the standby account wallet.
```javascript
const signed_vote = standby_wallet.sign(prepared_vote)
results += `\n\nSending AMMVote transaction ...`
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
```
Submit the signed transaction to the XRPL. Run the `checkAMM()` function to update the AMM's information in the AMM log on a successful transaction.
```javascript
const response_vote = await client.submitAndWait(signed_vote.tx_blob)
if (response_vote.result.meta.TransactionResult == "tesSUCCESS") {
results += `\n\nTransaction succeeded.`
checkAMM()
} else {
results += `\n\nError sending transaction: ${JSON.stringify(response_vote.result.meta.TransactionResult, null, 2)}`
}
} catch (error) {
results += `\n\n${error.message}`
}
```
Report the transaction results in the standby account log.
```javascript
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
client.disconnect()
}
```
### Calculate the Value of Your LP Tokens
This function gets your LP token balance and calculates what you can withdraw from the AMM.
```javascript
async function calculateLP() {
```
Connect to the XRP Ledger.
```javascript
let net = getNet()
const client = new xrpl.Client(net)
results = `\n\nConnecting to ${getNet()} ...`
standbyResultField.value = results
await client.connect()
results += '\n\nConnected.'
standbyResultField.value = results
```
Get the AMM information fields.
```javascript
const standby_wallet = standbyAccountField.value
const asset1_currency = asset1CurrencyField.value
const asset1_issuer = asset1IssuerField.value
const asset2_currency = asset2CurrencyField.value
const asset2_issuer = asset2IssuerField.value
```
Format the `amm_info` command based on the combination of `XRP` and tokens.
```javascript
let amm_info = null
if ( asset1_currency == "XRP" ) {
amm_info = {
"command": "amm_info",
"asset": {
"currency": "XRP"
},
"asset2": {
"currency": asset2_currency,
"issuer": asset2_issuer
}
}
} else if ( asset2_currency == "XRP" ) {
amm_info = {
"command": "amm_info",
"asset": {
"currency": asset1_currency,
"issuer": asset1_issuer
},
"asset2": {
"currency": "XRP"
}
}
} else {
amm_info = {
"command": "amm_info",
"asset": {
"currency": asset1_currency,
"issuer": asset1_issuer
},
"asset2": {
"currency": asset2_currency,
"issuer": asset2_issuer
}
}
}
```
Get the standby account wallet balances and AMM details. Wrap the code in a `try-catch` block to handle any errors.
```javascript
try {
// Get LP token balance.
standbyWalletBalances = await client.getBalances(standby_wallet)
const amm_info_result = await client.request(amm_info)
```
Get the AMM account address. Any LP tokens received from depositing to the AMM is considered an issued token by that AMM account. Use the AMM account to find the LP token in the wallet balances and get the LP token balance.
```javascript
// Get the AMM account address that issues LP tokens to depositors
ammAccount = amm_info_result.result.amm.account
const lpCurrency = standbyWalletBalances.find(item => item.issuer === ammAccount);
const lpBalance = lpCurrency ? lpCurrency.value : 'Currency not found';
```
Check the AMM `value` fields to format the response. `XRP` is only reported as drops and doesn't have a `value` field. Although there isn't a dedicated method to calculate what you can redeem your LP tokens for, the math to do so is simple. The code checks the percentage of LP tokens in circulation that you own, and then applies that same percentage to the total assets in the AMM to give you their redemption value.
```javascript
const my_share = lpBalance / amm_info_result.result.amm.lp_token.value
let my_asset1 = null
let my_asset2 = null
if ( amm_info_result.result.amm.amount.value && amm_info_result.result.amm.amount2.value ) {
my_asset1 = amm_info_result.result.amm.amount.value * my_share
my_asset2 = amm_info_result.result.amm.amount2.value * my_share
results += `\n\nI have a total of ${lpBalance} LP tokens that are worth:\n
${amm_info_result.result.amm.amount.currency}: ${my_asset1}
${amm_info_result.result.amm.amount2.currency}: ${my_asset2}`
} else if ( amm_info_result.result.amm.amount.value == undefined ) {
my_asset1 = (amm_info_result.result.amm.amount * my_share) / 1000000
my_asset2 = amm_info_result.result.amm.amount2.value * my_share
results += `\n\nI have a total of ${lpBalance} LP tokens that are worth:\n
XRP: ${my_asset1}
${amm_info_result.result.amm.amount2.currency}: ${my_asset2}`
} else {
my_asset1 = amm_info_result.result.amm.amount.value * my_share
my_asset2 = (amm_info_result.result.amm.amount2 * my_share) / 1000000
results += `\n\nI have a total of ${lpBalance} LP tokens that are worth:\n
${amm_info_result.result.amm.amount.currency}: ${my_asset1}
XRP: ${my_asset2}`
}
} catch (error) {
results += `\n\n${error.message}`
}
```
Report the transaction results in the standby account log.
```javascript
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
client.disconnect()
}
```
### Redeem Your LP Tokens
The code to redeem the LP tokens checks how many tokens you want to redeem, as well as the combination of assets to format `amm_info` and `AMMWithdraw`.
```javascript
async function redeemLP() {
```
Connect to the XRP Ledger.
```javascript
let net = getNet()
const client = new xrpl.Client(net)
results = `\n\nConnecting to ${getNet()} ...`
standbyResultField.value = results
await client.connect()
results += '\n\nConnected.'
standbyResultField.value = results
```
Get the AMM information fields.
```javascript
const standby_wallet = xrpl.Wallet.fromSeed(standbySeedField.value)
const asset1_currency = asset1CurrencyField.value
const asset1_issuer = asset1IssuerField.value
const asset2_currency = asset2CurrencyField.value
const asset2_issuer = asset2IssuerField.value
```
Format the `amm_info` command based on the combination of `XRP` and tokens.
```javascript
// Structure "amm_info" command based on asset combo.
let amm_info = null
if ( asset1_currency == "XRP" ) {
amm_info = {
"command": "amm_info",
"asset": {
"currency": "XRP"
},
"asset2": {
"currency": asset2_currency,
"issuer": asset2_issuer
}
}
} else if ( asset2_currency == "XRP" ) {
amm_info = {
"command": "amm_info",
"asset": {
"currency": asset1_currency,
"issuer": asset1_issuer
},
"asset2": {
"currency": "XRP"
}
}
} else {
amm_info = {
"command": "amm_info",
"asset": {
"currency": asset1_currency,
"issuer": asset1_issuer
},
"asset2": {
"currency": asset2_currency,
"issuer": asset2_issuer
}
}
}
```
Get the LP token information from the AMM.
```javascript
// Get LP token info.
let ammIssuer = null
let ammCurrency = null
const LPTokens = standbyLPField.value
try {
const amm_info_result = await client.request(amm_info)
ammIssuer = amm_info_result.result.amm.lp_token.issuer
ammCurrency = amm_info_result.result.amm.lp_token.currency
} catch (error) {
results += `\n\n${error.message}`
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
return
}
```
Format the `AMMWithdraw` transaction based on the combination of `XRP` and tokens. Add the LP token info into the transaction from the `amm_info` query.
```javascript
// Structure ammwithdraw transaction based on asset combo.
let ammwithdraw = null
if ( asset1_currency == "XRP" ) {
ammwithdraw = {
"TransactionType": "AMMWithdraw",
"Asset": {
"currency": "XRP"
},
"Asset2": {
"currency": asset2_currency,
"issuer": asset2_issuer
},
"Account": standby_wallet.address,
"LPTokenIn": {
currency: ammCurrency,
issuer: ammIssuer,
value: LPTokens
},
"Flags": 0x00010000
}
} else if ( asset2_currency == "XRP" ) {
ammwithdraw = {
"TransactionType": "AMMWithdraw",
"Asset": {
"currency": asset1_currency,
"issuer": asset1_issuer
},
"Asset2": {
"currency": "XRP"
},
"Account": standby_wallet.address,
"LPTokenIn": {
currency: ammCurrency,
issuer: ammIssuer,
value: LPTokens
},
"Flags": 0x00010000
}
} else {
ammwithdraw = {
"TransactionType": "AMMWithdraw",
"Asset": {
"currency": asset1_currency,
"issuer": asset1_issuer
},
"Asset2": {
"currency": asset2_currency,
"issuer": asset2_issuer
},
"Account": standby_wallet.address,
"LPTokenIn": {
currency: ammCurrency,
issuer: ammIssuer,
value: LPTokens
},
"Flags": 0x00010000
}
}
```
Prepare the transaction for submission. Wrap the submission in a `try-catch` block to handle any errors.
```javascript
try {
const prepared_withdraw = await client.autofill(ammwithdraw)
results += `\n\nPrepared transaction:\n${JSON.stringify(prepared_withdraw, null, 2)}`
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
```
Sign the prepared transaction with the standby account wallet.
```javascript
const signed_withdraw = standby_wallet.sign(prepared_withdraw)
results += `\n\nSending AMMWithdraw transaction ...`
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
```
Submit the signed transaction to the XRPL. Update the AMM info log and get wallet balances on a successful transaction.
```javascript
const response_withdraw = await client.submitAndWait(signed_withdraw.tx_blob)
if (response_withdraw.result.meta.TransactionResult == "tesSUCCESS") {
results += `\n\nTransaction succeeded.`
checkAMM()
getBalances()
} else {
results += `\n\nError sending transaction: ${JSON.stringify(response_withdraw.result.meta.TransactionResult, null, 2)}`
}
} catch (error) {
results += `\n\n${error.message}`
}
```
Report the transaction results to the standby account log.
```javascript
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
client.disconnect()
}
```

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docs/tutorials/javascript/amm/create-an-amm.md
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@@ -1,361 +0,0 @@
# Create an AMM
This example shows how to:
1. Check if an [AMM](/docs/concepts/tokens/decentralized-exchange/automated-market-makers) pair exists.
2. Issue a token.
3. Create an AMM pair with the issued tokens and XRP.
4. Create another AMM pair with two issued tokens.
[![Create AMM test harness](/docs/img/quickstart-create-amm1.png)](/docs/img/quickstart-create-amm1.png)
You can download the [Quickstart Samples](https://github.com/XRPLF/xrpl-dev-portal/tree/master/_code-samples/quickstart/js/) archive to try each of the samples in your own browser.
{% admonition type="info" name="Note" %}
Without the Quickstart Samples, you will not be able to try the examples that follow.
{% /admonition %}
## Usage
### Get Accounts
1. Open `11.create-amm.html` in a browser.
2. Select **Testnet** or **Devnet**
3. Get test accounts.
- If you have existing account seeds:
1. Paste account seeds in the **Seeds** field.
2. Click **Get Accounts from Seeds**.
- If you don't have account seeds:
1. Click **Get New Standby Account**.
2. Click **Get New Operational Account**.
[![Get account results](/docs/img/quickstart-create-amm2.png)](/docs/img/quickstart-create-amm2.png)
### Check AMM
Check if an AMM pair already exists. An AMM holds two different assets: at most one of these can be XRP, and one or both of them can be [tokens](/docs/concepts/tokens).
1. Enter a [currency code](/docs/references/protocol/data-types/currency-formats.md#currency-codes) in the **Asset 1 Currency** field. For example, `XRP`.
2. Enter a second currency code in the **Asset 2 Currency** field. For example, `TST`.
3. Enter the operational account address in the **Asset 2 Issuer** field.
4. Click **Check AMM**.
[![Check AMM results](/docs/img/quickstart-create-amm3.png)](/docs/img/quickstart-create-amm3.png)
### Create Trustline
Create a trustline from the operational account to the standby account. In the standby account fields:
1. Enter a maximum transfer limit in the **Amount** field, such as 10,000.
2. Enter the operational account address in the **Destination** field.
3. Enter a currency code in the **Currency** field. For example, `TST`.
4. Click **Create Trustline**.
[![Create trustline results](/docs/img/quickstart-create-amm4.png)](/docs/img/quickstart-create-amm4.png)
### Issue Tokens
Send issued tokens from the operational account to the standby account. In the operational account fields:
1. Select **Allow Rippling** and click **Configure Account**.
{% admonition type="info" name="Note" %}
This enables the `defaultRipple` flag on the issuing account, which is set to `false` by default. You need to enable this in order to trade tokens issued by the account. See [Configure Issuer Settings](../../how-tos/use-tokens/issue-a-fungible-token.md#3-configure-issuer-settings) to learn more.
{% /admonition %}
2. Enter a value in the **Amount** field, up to the maximum transfer amount you set in the trustline.
3. Enter the standby account address in the **Destination** field.
4. Enter the currency code from the trustline in the **Currency** field.
5. Click **Send Currency**.
[![Issue token results](/docs/img/quickstart-create-amm5.png)](/docs/img/quickstart-create-amm5.png)
### Create an XRP/Token AMM
Create a new AMM pool with XRP and the issued tokens.
1. Enter `XRP` in the **Asset 1 Currency** field.
2. Enter an amount of XRP in the **Asset 1 Amount** field. Save some `XRP` for later use in the tutorial.
3. Enter the currency code of your issued tokens in the **Asset 2 Currency** field.
4. Enter the operational account address in the **Asset 2 Issuer** field.
5. Enter an amount in the **Asset 2 Amount** field.
6. Click **Create AMM**.
{% admonition type="info" name="Note" %}
Save the seed values of the standby and operational accounts for subsequent AMM tutorials.
{% /admonition %}
[![Create AMM results](/docs/img/quickstart-create-amm6.png)](/docs/img/quickstart-create-amm6.png)
### Create a Token/Token AMM
Create a second AMM pool with two issued tokens.
1. Repeat the steps from [Create Trustline](#create-trustline), using a different currency code. For example, `FOO`.
2. Repeat the steps from [Issue Tokens](#issue-tokens), using the second currency.
3. Enter the first currency code in the **Asset 1 Currency** field.
4. Enter the operational account address in the **Asset 1 Issuer** field.
5. Enter an amount in the **Asset 1 Amount** field.
6. Enter the second currency code in the **Asset 2 Currency** field.
7. Enter the operaional account address in the **Asset 2 Issuer** field.
8. Enter an amount in the **Asset 2 Amount** field.
9. Click **Create AMM**.
[![Create AMM results](/docs/img/quickstart-create-amm7.png)](/docs/img/quickstart-create-amm7.png)
## Code Walkthrough
You can open `ripplex11-create-amm.js` from the [Quickstart Samples](https://github.com/XRPLF/xrpl-dev-portal/tree/master/_code-samples/quickstart/js/) to view the source code.
### Create AMM
This sends the `AMMCreate` transaction and creates a new AMM, using the initial assets provided. The code checks the token currency fields and formats the `AMMCreate` transaction based on the combination of `XRP` and custom tokens.
```javascript
async function createAMM() {
```
Connect to the XRP Ledger.
```javascript
let net = getNet()
const client = new xrpl.Client(net)
results = `\n\nConnecting to ${getNet()} ...`
standbyResultField.value = results
await client.connect()
results += '\n\nConnected.'
standbyResultField.value = results
```
Get the AMM information fields.
```javascript
const standby_wallet = xrpl.Wallet.fromSeed(standbySeedField.value)
const asset1_currency = asset1CurrencyField.value
const asset1_issuer = asset1IssuerField.value
const asset1_amount = asset1AmountField.value
const asset2_currency = asset2CurrencyField.value
const asset2_issuer = asset2IssuerField.value
const asset2_amount = asset2AmountField.value
```
Format the `AMMCreate` transaction based on the combination of `XRP` and tokens.
```javascript
let ammCreate = null
results += '\n\nCreating AMM ...'
standbyResultField.value = results
// AMMCreate requires burning one owner reserve. We can look up that amount
// (in drops) on the current network using server_state:
const ss = await client.request({"command": "server_state"})
const amm_fee_drops = ss.result.state.validated_ledger.reserve_inc.toString()
if (asset1_currency == 'XRP') {
ammCreate = {
"TransactionType": "AMMCreate",
"Account": standby_wallet.address,
"Amount": JSON.stringify(asset1_amount * 1000000), // convert XRP to drops
"Amount2": {
"currency": asset2_currency,
"issuer": asset2_issuer,
"value": asset2_amount
},
"TradingFee": 500, // 500 = 0.5%
"Fee": amm_fee_drops
}
} else if (asset2_currency =='XRP') {
ammCreate = {
"TransactionType": "AMMCreate",
"Account": standby_wallet.address,
"Amount": {
"currency": asset1_currency,
"issuer": asset1_issuer,
"value": asset1_amount
},
"Amount2": JSON.stringify(asset2_amount * 1000000), // convert XRP to drops
"TradingFee": 500, // 500 = 0.5%
"Fee": amm_fee_drops
}
} else {
ammCreate = {
"TransactionType": "AMMCreate",
"Account": standby_wallet.address,
"Amount": {
"currency": asset1_currency,
"issuer": asset1_issuer,
"value": asset1_amount
},
"Amount2": {
"currency": asset2_currency,
"issuer": asset2_issuer,
"value": asset2_amount
},
"TradingFee": 500, // 500 = 0.5%
"Fee": amm_fee_drops
}
}
```
Prepare the transaction for submission. Wrap the submission in a `try-catch` block to handle any errors.
```javascript
try {
const prepared_create = await client.autofill(ammCreate)
results += `\n\nPrepared transaction:\n${JSON.stringify(prepared_create, null, 2)}`
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
```
Sign the prepared transaction using the standy account wallet.
```javascript
const signed_create = standby_wallet.sign(prepared_create)
results += `\n\nSending AMMCreate transaction ...`
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
```
Submit the signed transaction to the XRPL.
```javascript
const amm_create = await client.submitAndWait(signed_create.tx_blob)
if (amm_create.result.meta.TransactionResult == "tesSUCCESS") {
results += `\n\nTransaction succeeded.`
} else {
results += `\n\nError sending transaction: ${JSON.stringify(amm_create.result.meta.TransactionResult, null, 2)}`
}
} catch (error) {
results += `\n\n${error.message}`
}
```
Report the transaction results in the standby account log. Run the `checkAMM()` function to update the AMM's information in the AMM log.
```javascript
standbyResultField.value = results
standbyResultField.scrollTop = standbyResultField.scrollHeight
checkAMM()
client.disconnect()
}
```
### Check AMM
This checks if an AMM already exists. While multiple tokens can share the same currency code, each issuer makes them unique. If the AMM pair exists, this responds with the AMM information, such as token pair, trading fees, etc.
```javascript
async function checkAMM() {
```
Connect to the XRP Ledger.
```javascript
let net = getNet()
const client = new xrpl.Client(net)
await client.connect()
```
Get the AMM info fields. When checking an AMM, you only need the currency code and issuer.
```javascript
// Gets the issuer and currency code
const asset1_currency = asset1CurrencyField.value
const asset1_issuer = asset1IssuerField.value
const asset2_currency = asset2CurrencyField.value
const asset2_issuer = asset2IssuerField.value
```
Format the `amm_info` command based on the combination of `XRP` and tokens.
```javascript
let amm_info_request = null
// Get AMM info transaction
if (asset1_currency == 'XRP') {
amm_info_request = {
"command": "amm_info",
"asset": {
"currency": "XRP"
},
"asset2": {
"currency": asset2_currency,
"issuer": asset2_issuer
},
"ledger_index": "validated"
}
} else if (asset2_currency =='XRP') {
amm_info_request = {
"command": "amm_info",
"asset": {
"currency": asset1_currency,
"issuer": asset1_issuer
},
"asset2": {
"currency": "XRP"
},
"ledger_index": "validated"
}
} else {
amm_info_request = {
"command": "amm_info",
"asset": {
"currency": asset1_currency,
"issuer": asset1_issuer
},
"asset2": {
"currency": asset2_currency,
"issuer": asset2_issuer
},
"ledger_index": "validated"
}
}
```
Submit the request in a `try-catch` block and update the AMM log.
```javascript
try {
const amm_info_result = await client.request(amm_info_request)
ammInfo = `AMM Info:\n\n${JSON.stringify(amm_info_result.result.amm, null, 2)}`
} catch(error) {
ammInfo = `AMM Info:\n\n${error}`
}
ammInfoField.value = ammInfo
client.disconnect()
}
```

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@@ -1,640 +0,0 @@
# Trade with an AMM Auction Slot
Follow the steps from the [Create an AMM](/docs/tutorials/javascript/amm/create-an-amm/) tutorial before proceeding.
This example shows how to:
1. Calculate the exact cost of swapping one token for another in an [AMM](/docs/concepts/tokens/decentralized-exchange/automated-market-makers) pool.
2. Check the difference in trading fees with and without an auction slot.
3. Bid on an auction slot with LP tokens.
4. Create an offer to swap tokens with the AMM.
[![Trade with Auction Slot Test Harness](/docs/img/quickstart-trade-auction-slot1.png)](/docs/img/quickstart-trade-auction-slot1.png)
You can download the [Quickstart Samples](https://github.com/XRPLF/xrpl-dev-portal/tree/master/_code-samples/quickstart/js/) archive to try each of the samples in your own browser.
{% admonition type="info" name="Note" %}
Without the Quickstart Samples, you will not be able to try the examples that follow.
{% /admonition %}
## Usage
### Get Accounts
1. Open `13.trade-with-auction-slot.html` in a browser.
2. Select **Testnet** or **Devnet**
3. Get test accounts.
- If you have existing account seeds:
1. Paste account seeds in the **Seeds** field.
2. Click **Get Accounts from Seeds**.
- If you don't have account seeds:
1. Click **Get New Standby Account**.
2. Click **Get New Operational Account**.
[![Get account results](/docs/img/quickstart-trade-auction-slot2.png)](/docs/img/quickstart-trade-auction-slot2.png)
### Get the AMM
Use the information from either the XRP/Token or Token/Token AMM you created in [Create an AMM](/docs/tutorials/javascript/amm/create-an-amm/#create-an-xrp/token-amm).
1. Enter a [currency code](/docs/references/protocol/data-types/currency-formats.md#currency-codes) in the **Asset 1 Currency** field. For example, `XRP`.
2. Enter a second currency code in the **Asset 2 Currency** field. For example, `TST`.
3. Enter the operational account address in the **Asset 2 Issuer** field.
4. Click **Check AMM**.
[![Get AMM results](/docs/img/quickstart-trade-auction-slot3.png)](/docs/img/quickstart-trade-auction-slot3.png)
### Estimate Costs
Get a new standby account to ensure you aren't using an account with an auction slot already.
1. Click **Get New Standby Account**.
2. Under the **Taker Pays** column:
- Enter a currency code in the **Currency** field. For example, `TST`.
- Enter the operational account address in the **Issuer** field.
- Enter an **Amount**. For example, `10`.
3. Under the **Taker Gets** column, enter a currency code in the **Currency** field. For example, `XRP`.
4. Click **Estimate Cost**.
5. Save the values given by the estimate.
[![Estimate costs results](/docs/img/quickstart-trade-auction-slot4.png)](/docs/img/quickstart-trade-auction-slot4.png)
### Bid for the Auction Slot
Make a single-asset deposit to the AMM to receive the required LP tokens for the auction slot bid. You can deposit either asset from the cost estimator.
1. Enter the estimated deposit amount in either **Asset 1 Amount** or **Asset 2 Amount**. For example, `0.004012` in **Asset 1 Amount**.
2. Click **Add to AMM**.
3. Enter the estimated bid amount in the **LP Tokens** field. For example, `6.326`.
4. Click **Bid Auction Slot**.
[![Bid auction slot results](/docs/img/quickstart-trade-auction-slot5.png)](/docs/img/quickstart-trade-auction-slot5.png)
### Swap Tokens with the AMM
Get a new estimate to update the expected cost for swapping tokens.
1. Click **Estimate Cost**.
2. Under the **Taker Gets Column**, enter an **Amount**. Use the expected cost with an auction slot from the estimate. For example, `1.112113`.
3. Click **Swap Tokens**.
[![Swap tokens with AMM results](/docs/img/quickstart-trade-auction-slot6.png)](/docs/img/quickstart-trade-auction-slot6.png)
## Code Walkthrough (ripplex13a-trade-with-auction-slot.js)
You can open `ripplex13a-trade-with-auction-slot.js` from the [Quickstart Samples](https://github.com/XRPLF/xrpl-dev-portal/tree/master/_code-samples/quickstart/js/) to view the source code.
### Estimate AMM Costs
This function checks the cost of interactions with the AMM, such as deposits, auction slot bids, and token swaps.
```javascript
async function estimateCost() {
```
Connect to the XRP Ledger.
```javascript
let net = getNet()
const client = new xrpl.Client(net)
results = `\n\nConnecting to ${getNet()} ...`
standbyResultField.value = results
await client.connect()
results += '\n\nConnected.'
standbyResultField.value = results
```
Format the `amm_info` command and get the AMM information. This code is wrapped in a `try-catch` block to handle any errors.
```javascript
try {
const asset1_currency = asset1CurrencyField.value
const asset1_issuer = asset1IssuerField.value
const asset2_currency = asset2CurrencyField.value
const asset2_issuer = asset2IssuerField.value
// Look up AMM info
let asset1_info = null
let asset2_info = null
if ( asset1_currency == 'XRP' ) {
asset1_info = {
"currency": "XRP"
}
} else {
asset1_info = {
"currency": asset1_currency,
"issuer": asset1_issuer
}
}
if ( asset2_currency == 'XRP' ) {
asset2_info = {
"currency": "XRP"
}
} else {
asset2_info = {
"currency": asset2_currency,
"issuer": asset2_issuer
}
}
const amm_info = (await client.request({
"command": "amm_info",
"asset": asset1_info,
"asset2": asset2_info
}))
// Save relevant AMM info for calculations
const lpt = amm_info.result.amm.lp_token
const pool_asset1 = amm_info.result.amm.amount
const pool_asset2 = amm_info.result.amm.amount2
const full_trading_fee = amm_info.result.amm.trading_fee
const discounted_fee = amm_info.result.amm.auction_slot.discounted_fee
const old_bid = amm_info.result.amm.auction_slot.price.value
const time_interval = amm_info.result.amm.auction_slot.time_interval
results += `\n\nTrading Fee: ${full_trading_fee/1000}%\nDiscounted Fee: ${discounted_fee/1000}%`
```
Save the taker pays and taker gets fields; use these values to get the total amount of each asset in the AMM pool, using large significant digits for precise calculations. This also checks if the requested token amount is larger than what is available in the AMM pool, stopping the code if `true`.
```javascript
// Save taker pays and gets values.
const takerPays = {
"currency": standbyTakerPaysCurrencyField.value,
"issuer": standbyTakerPaysIssuerField.value,
"amount": standbyTakerPaysAmountField.value
}
const takerGets = {
"currency": standbyTakerGetsCurrencyField.value,
"issuer": standbyTakerGetsIssuerField.value,
"amount": standbyTakerGetsAmountField.value
}
// Get amount of assets in the pool.
// Convert values to BigNumbers with the appropriate precision.
// Tokens always have 15 significant digits;
// XRP is precise to integer drops, which can be as high as 10^17
let asset_out_bn = null
let pool_in_bn = null
let pool_out_bn = null
let isAmmAsset1Xrp = false
let isAmmAsset2Xrp = false
if ( takerPays.currency == 'XRP' ) {
asset_out_bn = BigNumber(xrpl.xrpToDrops(takerPays.amount)).precision(17)
} else {
asset_out_bn = BigNumber(takerPays.amount).precision(15)
}
if ( takerGets.currency == 'XRP' && asset1_currency == 'XRP' ) {
pool_in_bn = BigNumber(pool_asset1).precision(17)
isAmmAsset1Xrp = true
} else if ( takerGets.currency == 'XRP' && asset2_currency == 'XRP' ) {
pool_in_bn = BigNumber(pool_asset2).precision(17)
isAmmAsset2Xrp = true
} else if ( takerGets.currency == asset1_currency ) {
pool_in_bn = BigNumber(pool_asset1.value).precision(15)
} else {
pool_in_bn = BigNumber(pool_asset2.value).precision(15)
}
if (takerPays.currency == 'XRP' && asset1_currency == 'XRP' ) {
pool_out_bn = BigNumber(pool_asset1).precision(17)
} else if ( takerPays.currency == 'XRP' && asset2_currency == 'XRP' ) {
pool_out_bn = BigNumber(pool_asset2).precision(17)
} else if ( takerPays.currency == asset1_currency ) {
pool_out_bn = BigNumber(pool_asset1.value).precision(15)
} else {
pool_out_bn = BigNumber(pool_asset2.value).precision(15)
}
if ( takerPays.currency == 'XRP' && parseFloat(takerPays.amount) > parseFloat(xrpl.dropsToXrp(pool_out_bn)) ) {
results += `\n\nRequested ${takerPays.amount} ${takerPays.currency}, but AMM only holds ${xrpl.dropsToXrp(pool_out_bn)}. Quitting.`
standbyResultField.value = results
client.disconnect()
return
} else if ( parseFloat(takerPays.amount) > parseFloat(pool_out_bn) ) {
results += `\n\nRequested ${takerPays.amount} ${takerPays.currency}, but AMM only holds ${pool_out_bn}. Quitting.`
standbyResultField.value = results
client.disconnect()
return
}
```
Use [AMM helper functions](https://github.com/XRPLF/rippled/blob/2d1854f354ff8bb2b5671fd51252c5acd837c433/src/ripple/app/misc/impl/AMMHelpers.cpp) to estimate values for:
- Cost to swap token without an auction slot.
- Cost to swap token with an auction slot.
- LP tokens to win an auction slot. This value factors the increase in the minimum bid of having new LP tokens issued to you from your deposit.
- The amount of tokens for single-asset deposits to get the required LP tokens to win the auction slot.
```javascript
// Use AMM's SwapOut formula to figure out how much of the takerGets asset
// you have to pay to receive the target amount of takerPays asset
const unrounded_amount = swapOut(asset_out_bn, pool_in_bn, pool_out_bn, full_trading_fee)
// Drop decimal places and round ceiling to ensure you pay in enough.
const swap_amount = unrounded_amount.dp(0, BigNumber.ROUND_CEIL)
// Helper function to convert drops to XRP in log window
function convert(currency, amount) {
if ( currency == 'XRP' ) {
amount = xrpl.dropsToXrp(amount)
}
return amount
}
results += `\n\nExpected cost for ${takerPays.amount} ${takerPays.currency}: ${convert(takerGets.currency, swap_amount)} ${takerGets.currency}`
// Use SwapOut to calculate discounted swap amount with auction slot
const raw_discounted = swapOut(asset_out_bn, pool_in_bn, pool_out_bn, discounted_fee)
const discounted_swap_amount = raw_discounted.dp(0, BigNumber.ROUND_CEIL)
results += `\n\nExpected cost with auction slot for ${takerPays.amount} ${takerPays.currency}: ${convert(takerGets.currency, discounted_swap_amount)} ${takerGets.currency}`
// Calculate savings by using auction slot
const potential_savings = swap_amount.minus(discounted_swap_amount)
results += `\nPotential savings: ${convert(takerGets.currency, potential_savings)} ${takerGets.currency}`
// Calculate the cost of winning the auction slot, in LP Tokens.
const auction_price = auctionDeposit(old_bid, time_interval, full_trading_fee, lpt.value).dp(3, BigNumber.ROUND_CEIL)
results += `\n\nYou can win the current auction slot by bidding ${auction_price} LP Tokens.`
// Calculate how much to add for a single-asset deposit to receive the target LP Token amount
let deposit_for_bid_asset1 = null
let deposit_for_bid_asset2 = null
if ( isAmmAsset1Xrp == true ) {
deposit_for_bid_asset1 = xrpl.dropsToXrp(ammAssetIn(pool_asset1, lpt.value, auction_price, full_trading_fee).dp(0, BigNumber.ROUND_CEIL))
} else {
deposit_for_bid_asset1 = ammAssetIn(pool_asset1.value, lpt.value, auction_price, full_trading_fee).dp(15, BigNumber.ROUND_CEIL)
}
if ( isAmmAsset2Xrp == true ) {
deposit_for_bid_asset2 = xrpl.dropsToXrp(ammAssetIn(pool_asset2, lpt.value, auction_price, full_trading_fee).dp(0, BigNumber.ROUND_CEIL))
} else {
deposit_for_bid_asset2 = ammAssetIn(pool_asset2.value, lpt.value, auction_price, full_trading_fee).dp(15, BigNumber.ROUND_CEIL)
}
if ( isAmmAsset1Xrp == true ) {
results += `\n\nMake a single-asset deposit to the AMM of ${deposit_for_bid_asset1} XRP or ${deposit_for_bid_asset2} ${pool_asset2.currency} to get the required LP Tokens.`
} else if ( isAmmAsset2Xrp == true ) {
results += `\n\nMake a single-asset deposit to the AMM of ${deposit_for_bid_asset1} ${pool_asset1.currency} or ${deposit_for_bid_asset2} XRP to get the required LP Tokens.`
} else {
results += `\n\nMake a single-asset deposit to the AMM of ${deposit_for_bid_asset1} ${pool_asset1.currency} or ${deposit_for_bid_asset2} ${pool_asset2.currency} to get the required LP Tokens.`
}
} catch (error) {
results += `\n\n${error.message}`
}
```
Report the estimated values and close the client connection.
```javascript
standbyResultField.value = results
client.disconnect()
}
```
### Bid on the Auction Slot
This function bids on the AMM auction slot, using LP tokens.
```javascript
async function bidAuction() {
```
Connect to the ledger.
```javascript
let net = getNet()
const client = new xrpl.Client(net)
results = `\n\nConnecting to ${getNet()} ...`
standbyResultField.value = results
await client.connect()
results += '\n\nConnected.'
standbyResultField.value = results
```
Format the asset values, depending on if it's `XRP` or a token. Wrap the code in a `try-catch` block to handle any errors.
```javascript
try {
const standby_wallet = xrpl.Wallet.fromSeed(standbySeedField.value)
const asset1_currency = asset1CurrencyField.value
const asset1_issuer = asset1IssuerField.value
const asset2_currency = asset2CurrencyField.value
const asset2_issuer = asset2IssuerField.value
const valueLPT = standbyLPField.value
// Look up AMM info
let asset1_info = null
let asset2_info = null
if ( asset1_currency == 'XRP' ) {
asset1_info = {
"currency": "XRP"
}
} else {
asset1_info = {
"currency": asset1_currency,
"issuer": asset1_issuer
}
}
if ( asset2_currency == 'XRP' ) {
asset2_info = {
"currency": "XRP"
}
} else {
asset2_info = {
"currency": asset2_currency,
"issuer": asset2_issuer
}
}
const amm_info = (await client.request({
"command": "amm_info",
"asset": asset1_info,
"asset2": asset2_info
}))
// Save relevant AMM info for calculations
const lpt = amm_info.result.amm.lp_token
results += '\n\nBidding on auction slot ...'
standbyResultField.value = results
```
Submit the `AMMBid` transaction.
```javascript
const bid_result = await client.submitAndWait({
"TransactionType": "AMMBid",
"Account": standby_wallet.address,
"Asset": asset1_info,
"Asset2": asset2_info,
"BidMax": {
"currency": lpt.currency,
"issuer": lpt.issuer,
"value": valueLPT
},
"BidMin": {
"currency": lpt.currency,
"issuer": lpt.issuer,
"value": valueLPT
} // So rounding doesn't leave dust amounts of LPT
}, {autofill: true, wallet: standby_wallet})
if (bid_result.result.meta.TransactionResult == "tesSUCCESS") {
results += `\n\nTransaction succeeded.`
checkAMM()
} else {
results += `\n\nError sending transaction: ${JSON.stringify(bid_result.result.meta.TransactionResult, null, 2)}`
}
} catch (error) {
results += `\n\n${error.message}`
}
```
Report the results.
```javascript
standbyResultField.value = results
client.disconnect()
}
```
### Swap AMM Tokens
This function submits an `OfferCreate` transaction, using precise values to format the transaction and have the AMM completely consume the offer.
```javascript
async function swapTokens() {
```
Connect to the XRP Ledger.
```javascript
let net = getNet()
const client = new xrpl.Client(net)
results = `\n\nConnecting to ${getNet()} ...`
standbyResultField.value = results
await client.connect()
results += '\n\nConnected.'
standbyResultField.value = results
```
Get the taker pays and taker gets fields and format the amounts depending on if it's `XRP` or a custom token. Wrap the code in a `try-catch` block to handle any errors.
```javascript
try {
const standby_wallet = xrpl.Wallet.fromSeed(standbySeedField.value)
const takerPaysCurrency = standbyTakerPaysCurrencyField.value
const takerPaysIssuer = standbyTakerPaysIssuerField.value
const takerPaysAmount = standbyTakerPaysAmountField.value
const takerGetsCurrency = standbyTakerGetsCurrencyField.value
const takerGetsIssuer = standbyTakerGetsIssuerField.value
const takerGetsAmount = standbyTakerGetsAmountField.value
let takerPays = null
let takerGets = null
if ( takerPaysCurrency == 'XRP' ) {
takerPays = xrpl.xrpToDrops(takerPaysAmount)
} else {
takerPays = {
"currency": takerPaysCurrency,
"issuer": takerPaysIssuer,
"value": takerPaysAmount
}
}
if ( takerGetsCurrency == 'XRP' ) {
takerGets = xrpl.xrpToDrops(takerGetsAmount)
} else {
takerGets = {
"currency": takerGetsCurrency,
"issuer": takerGetsIssuer,
"value": takerGetsAmount
}
}
results += '\n\nSwapping tokens ...'
standbyResultField.value = results
```
Submit the `OfferCreate` transaction.
```javascript
const offer_result = await client.submitAndWait({
"TransactionType": "OfferCreate",
"Account": standby_wallet.address,
"TakerPays": takerPays,
"TakerGets": takerGets
}, {autofill: true, wallet: standby_wallet})
if (offer_result.result.meta.TransactionResult == "tesSUCCESS") {
results += `\n\nTransaction succeeded.`
checkAMM()
} else {
results += `\n\nError sending transaction: ${JSON.stringify(offer_result.result.meta.TransactionResult, null, 2)}`
}
} catch (error) {
results += `\n\n${error.message}`
}
```
Report the results.
```javascript
standbyResultField.value = results
client.disconnect()
}
```
## Code Walkthrough (ripplex13b-amm-formulas.js)
You can open `ripplex13b-amm-formulas.js` from the [Quickstart Samples](https://github.com/XRPLF/xrpl-dev-portal/tree/master/_code-samples/quickstart/js/) to view the source code. This tutorial uses three of the available [AMM helper functions](https://github.com/XRPLF/rippled/blob/2d1854f354ff8bb2b5671fd51252c5acd837c433/src/ripple/app/misc/impl/AMMHelpers.cpp).
### swapOut()
The `swapOut()` function calculates how much of an asset you must deposit into an AMM to receive a specified amount of the paired asset. The input asset is what you're adding to the pool (paying), and the output asset is what you're receiving from the pool (buying).
The formula used is based on [AMM Swap](https://github.com/XRPLF/XRPL-Standards/tree/master/XLS-0030-automated-market-maker#25-amm-swap), defined in XLS-30.
| Parameter | Type | Description |
|-----------|------|-------------|
| asset_out_bn | BigNumber | The target amount to receive from the AMM. |
| pool_in_bn | BigNumber | The amount of the input asset in the AMM's pool before the swap. |
| pool_out_bn | BigNumber | The amount of the output asset in the AMM's pool before the swap. |
| trading_fee | int | The trading fee as an integer {0, 1000} where 1000 represents a 1% fee. |
| Returns | Type | Description |
|---------|------|-------------|
| Return Value | BigNumber | The amount of the input asset that must be swapped in to receive the target output amount. Unrounded, because the number of decimals depends on if this is drops of XRP or a decimal amount of a token; since this is a theoretical input to the pool, it should be rounded up (ceiling) to preserve the pool's constant product. |
```javascript
function swapOut(asset_out_bn, pool_in_bn, pool_out_bn, trading_fee) {
return ( ( pool_in_bn.multipliedBy(pool_out_bn) ).dividedBy(
pool_out_bn.minus(asset_out_bn)
).minus(pool_in_bn)
).dividedBy(feeMult(trading_fee))
}
```
### auctionDeposit()
The `auctionDeposit()` calculates how many LP tokens you need to spend to win the auction slot. The formula assumes you don't have any LP tokens and factors in the increase in LP tokens issued when you deposit assets. If you already have LP tokens, you can use the `auctionPrice()` function instead.
The formula used is based on the [slot pricing algorithm](https://github.com/XRPLF/XRPL-Standards/tree/master/XLS-0030-automated-market-maker#411-slot-pricing) defined in XLS-30.
```javascript
function auctionDeposit(old_bid, time_interval, trading_fee, lpt_balance) {
const tfee_decimal = feeDecimal(trading_fee)
const lptokens = BigNumber(lpt_balance)
const b = BigNumber(old_bid)
let outbidAmount = BigNumber(0) // This is the case if time_interval >= 20
if (time_interval == 0) {
outbidAmount = b.multipliedBy("1.05")
} else if (time_interval <= 19) {
const t60 = BigNumber(time_interval).multipliedBy("0.05").exponentiatedBy(60)
outbidAmount = b.multipliedBy("1.05").multipliedBy(BigNumber(1).minus(t60))
}
const new_bid = lptokens.plus(outbidAmount).dividedBy(
BigNumber(25).dividedBy(tfee_decimal).minus(1)
).plus(outbidAmount)
// Significant digits for the deposit are limited by total LPTokens issued
// so we calculate lptokens + deposit - lptokens to determine where the
// rounding occurs. We use ceiling/floor to make sure the amount we receive
// after rounding is still enough to win the auction slot.
const rounded_bid = new_bid.plus(lptokens).precision(15, BigNumber.CEILING
).minus(lptokens).precision(15, BigNumber.FLOOR)
return rounded_bid
}
```
### ammAssetIn()
The `ammAssetIn()` function calculates how much to add in a single-asset deposit to receive a specified amount of LP tokens.
| Parameter | Type | Description |
|-----------|------|-------------|
| pool_in | string | The quantity of the input asset the pool already has. |
| lpt_balance | string | The quantity of LP tokens already issued by the AMM. |
| desired_lpt | string | The quantity of new LP tokens you want to receive. |
| trading_fee | int | The trading fee as an integer {0, 1000} where 1000 represents a 1% fee. |
```javascript
function ammAssetIn(pool_in, lpt_balance, desired_lpt, trading_fee) {
// convert inputs to BigNumber
const lpTokens = BigNumber(desired_lpt)
const lptAMMBalance = BigNumber(lpt_balance)
const asset1Balance = BigNumber(pool_in)
const f1 = feeMult(trading_fee)
const f2 = feeMultHalf(trading_fee).dividedBy(f1)
const t1 = lpTokens.dividedBy(lptAMMBalance)
const t2 = t1.plus(1)
const d = f2.minus( t1.dividedBy(t2) )
const a = BigNumber(1).dividedBy( t2.multipliedBy(t2))
const b = BigNumber(2).multipliedBy(d).dividedBy(t2).minus(
BigNumber(1).dividedBy(f1)
)
const c = d.multipliedBy(d).minus( f2.multipliedBy(f2) )
return asset1Balance.multipliedBy(solveQuadraticEq(a,b,c))
}
```
Compute the quadratic formula. This is a helper function for `ammAssetIn()`. Parameters and return value are `BigNumber` instances.
```javascript
function solveQuadraticEq(a,b,c) {
const b2minus4ac = b.multipliedBy(b).minus(
a.multipliedBy(c).multipliedBy(4)
)
return ( b.negated().plus(b2minus4ac.sqrt()) ).dividedBy(a.multipliedBy(2))
}
```

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---
html: build-a-browser-wallet-in-javascript.html
parent: javascript.html
targets:
- en
- ja # TODO: translate this page
seo:
description: Build a graphical browser wallet for the XRPL using Javascript.
---
# Build a Browser Wallet in JavaScript
<!-- STYLE_OVERRIDE: wallet -->
This tutorial demonstrates how to build a browser wallet for the XRP Ledger using the Javascript programming language and various libraries. This application can be used as a starting point for building a more complete and powerful application, as a reference point for building comparable apps, or as a learning experience to better understand how to integrate XRP Ledger functionality into a larger project.
## Prerequisites
To complete this tutorial, you should meet the following guidelines:
1. You have [Node.js](https://nodejs.org/en/download/) v14 or higher installed.
2. You have [Yarn](https://yarnpkg.com/en/docs/install) (v1.17.3 or higher) installed.
3. You are somewhat familiar with coding with JavaScript and have completed the [Get Started Using JavaScript](./get-started.md) tutorial.
## Source Code
You can find the complete source code for all of this tutorial's examples in the {% repo-link path="_code-samples/build-a-browser-wallet/js/" %}code samples section of this website's repository{% /repo-link %}.
## Goals
At the end of this tutorial, you should be able to build a simple XRP wallet displayed below.
![Home Page Screenshot](/docs/img/js-wallet-home.png)
This application can:
- Show updates to the XRP Ledger in real-time.
- View any XRP Ledger account's activity, including showing how much XRP was delivered by each transaction.
- Show how much XRP is set aside for the account's [reserve requirement](../../../concepts/accounts/reserves.md).
- Send [direct XRP payments](../../../concepts/payment-types/direct-xrp-payments.md), and provide feedback about the intended destination address, including:
- Displaying your account's available balance
- Verifying that the destination address is valid
- Validating the account has enough XRP to send
- Allowing you to specify a destination tag
## Steps
Before you begin, make sure you have the prerequisites installed. Check your node version by running `node -v`. If necessary, [download Node.js](https://nodejs.org/en/download/).
{% admonition type="success" name="Tip" %}If you get stuck while doing this tutorial, or working on another project, feel free to ask for help in the XRPL's [Developer Discord](https://discord.com/invite/KTNmhJDXqa).{% /admonition %}
### 1. Set up the project
1. Navigate to the directory that you want to create the project in.
2. Create a new Vite project:
```bash
yarn create vite simple-xrpl-wallet --template vanilla
```
3. Create or modify the file `package.json` to have the following contents:
{% code-snippet file="/_code-samples/build-a-browser-wallet/js/package.json" language="js" /%}
- Alternatively you can also do `yarn add <package-name>` for each individual package to add them to your `package.json` file.
4. Install dependencies:
```bash
yarn
```
5. Create a new file `.env` in the root directory of the project and add the following variables:
```bash
CLIENT="wss://s.altnet.rippletest.net:51233/"
EXPLORER_NETWORK="testnet"
SEED="s████████████████████████████"
```
6. Change the seed to your own seed. You can get credentials from [the Testnet faucet](/resources/dev-tools/xrp-faucets).
7. Set up a Vite bundler. Create a file named `vite.config.js` in the root directory of the project and fill it with the following code:
{% code-snippet file="/_code-samples/build-a-browser-wallet/js/vite.config.js" language="js" /%}
8. Add script to `package.json`
In your `package.json` file, add the following section if it's not there already:
```json
"scripts": {
"dev": "vite"
}
```
### 2. Create the Home Page (Displaying Account & Ledger Details)
In this step, we create a home page that displays account and ledger details.
![Home Page Screenshot](/docs/img/js-wallet-home.png)
1. If not already present, create new files in the root folder named `index.html`, `index.js` and `index.css`.
2. Make a new folder named `src` in the root directory of the project.
3. Copy the contents of {% repo-link path="_code-samples/build-a-browser-wallet/js/index.html" %}index.html{% /repo-link %} in your code.
4. Add styling to your {% repo-link path="_code-samples/build-a-browser-wallet/js/index.css" %}index.css{% /repo-link %} file by following the link.
This basic setup creates a homepage and applies some visual styles. The goal is for the homepage to:
- Display our account info
- Show what's happening on the ledger
- And add a little logo for fun
To make that happen, we need to connect to the XRP Ledger and look up the account and the latest validated ledger.
5. In the `src/` directory, make a new folder named `helpers`. Create a new file there named `get-wallet-details.js` and define a function named `getWalletDetails` there. This function uses the [account_info method](../../../references/http-websocket-apis/public-api-methods/account-methods/account_info.md) to fetch account details and the [server_info method](../../../references/http-websocket-apis/public-api-methods/server-info-methods/server_info.md) to calculate the current [reserves](../../../concepts/accounts/reserves.md). The code to do all this is as follows:
{% code-snippet file="/_code-samples/build-a-browser-wallet/js/src/helpers/get-wallet-details.js" language="js" /%}
6. Now, let's add the code to `index.js` file to fetch the account and ledger details and display them on the home page. Copy the code written below to the `index.js` file. Here we render the wallet details using the function we defined in `get-wallet-details.js`. In order to make sure we have up to date ledger data, we are using the [ledger stream](../../../references/http-websocket-apis/public-api-methods/subscription-methods/subscribe.md#ledger-stream) to listen for ledger close events.
{% code-snippet file="/_code-samples/build-a-browser-wallet/js/index.js" language="js" /%}
7. In the `helpers` folder, add {% repo-link path="_code-samples/build-a-browser-wallet/js/src/helpers/render-xrpl-logo.js" %}render-xrpl-logo.js{% /repo-link %} to handle displaying a logo.
8. Finally create a new folder named `assets` in the `src/` directory and add the file {% repo-link path="_code-samples/build-a-browser-wallet/js/src/assets/xrpl.svg" %}`xrpl.svg`{% /repo-link %} there.
These files are used to render the XRPL logo for aesthetic purposes.
The one other thing we do here is add events to two buttons - one to send XRP and one to view transaction history. They won't work just yet — we'll implement them in the next steps.
Now the application is ready to run. You can start it in dev mode using the following command:
```bash
yarn dev
```
Your terminal should output a URL which you can use to open your app in a browser. This dev site automatically updates to reflect any changes you make to the code.
### 3. Create the Send XRP Page
Now that we've created the home page, we can move on to the "Send XRP" page. This is what allows this wallet to manage your account's funds.
![Send XRP Page Screenshot](/docs/img/js-wallet-send-xrp.png)
1. Create a folder named `send-xrp` in the `src` directory.
2. Inside the `send-xrp` folder, create two files named `send-xrp.js` and `send-xrp.html`.
3. Copy the contents of the {% repo-link path="_code-samples/build-a-browser-wallet/js/src/send-xrp/send-xrp.html" %}send-xrp.html{% /repo-link %} file to your `send-xrp.html` file. The provided HTML code includes three input fields for the destination address, amount, and destination tag, each with their corresponding labels.
4. Now that we have the HTML code, let's add the JavaScript code. In the `helpers` folder, create a new file named `submit-transaction.js` and copy the code written below to the file. In this file, we are using the [submit](../../../references/http-websocket-apis/public-api-methods/transaction-methods/submit.md) method to submit the transaction to the XRPL. Before submitting every transaction needs to be signed by a wallet, learn more about [signing](../../../references/http-websocket-apis/admin-api-methods/signing-methods/sign.md) a transaction.
{% code-snippet file="/_code-samples/build-a-browser-wallet/js/src/helpers/submit-transaction.js" language="js" /%}
5. Now back to the `send-xrp.js` file, copy the code written below to the file. In this piece of code we are first getting all the DOM elements from HTML and adding event listners to update & validate the fields based on the user input. Using `renderAvailableBalance` method we display the current available balance of the wallet. `validateAddress` function validates the user address, and the amount is validated using a regular expression. When all the fields are filled with correct inputs, we call the `submitTransaction` function to submit the transaction to the ledger.
{% code-snippet file="/_code-samples/build-a-browser-wallet/js/src/send-xrp/send-xrp.js" language="js" /%}
You can now click 'Send XRP' to try creating your own transaction! You can use this example to send XRP to the testnet faucet to try it out.
Testnet faucet account: `rHbZCHJSGLWVMt8D6AsidnbuULHffBFvEN`
Amount: 9
Destination Tag: (Not usually necessary unless you're paying an account tied to an exchange)
![Send XRP Transaction Screenshot](/docs/img/js-wallet-send-xrp-transaction-details.png)
### 4. Create the Transactions Page
Now that we have created the home page and the send XRP page, let's create the transactions page that will display the transaction history of the account. In order to see what's happening on the ledger, we're going to display the following fields:
- Account: The account that sent the transaction.
- Destination: The account that received the transaction.
- Transaction Type: The type of transaction.
- Result: The result of the transaction.
- Delivered amount: The amount of XRP or tokens delivered by the transaction, if applicable.
- Link: A link to the transaction on the XRP Ledger Explorer.
{% admonition type="warning" name="Caution" %}When displaying how much money a transaction delivered, always use the `delivered_amount` field from the metadata, not the `Amount` field from the transaction instructions. [Partial Payments](../../../concepts/payment-types/partial-payments.md) can deliver much less than the stated `Amount` and still be successful.{% /admonition %}
![Transactions Page Screenshot](/docs/img/js-wallet-transaction.png)
1. Create a folder named `transaction-history` in the src directory.
2. Create a file named `transaction-history.js` and copy the code written below.
{% code-snippet file="/_code-samples/build-a-browser-wallet/js/src/transaction-history/transaction-history.js" language="js" /%}
This code uses [account_tx](../../../references/http-websocket-apis/public-api-methods/account-methods/account_tx.md) to fetch transactions we've sent to and from this account. In order to get all the results, we're using the `marker` parameter to paginate through the incomplete list of transactions until we reach the end.
3. Create a file named `transaction-history.html` and copy the code from {% repo-link path="_code-samples/build-a-browser-wallet/js/src/transaction-history/transaction-history.html" %}transaction-history.html{% /repo-link %} into it.
`transaction-history.html` defines a table which displays the fields mentioned above.
You can use this code as a starting point for displaying your account's transaction history. If you want an additional challenge, try expanding it to support different transaction types (e.g. [TrustSet](../../../references/protocol/transactions/types/trustset.md)). If you want inspiration for how to handle this, you can check out the [XRP Ledger Explorer](https://livenet.xrpl.org/) to see how the transaction details are displayed.
## Next Steps
Now that you have a functional wallet, you can take it in several new directions. The following are a few ideas:
- You could support more of the XRP Ledger's [transaction types](../../../references/protocol/transactions/types/index.md) including [tokens](../../../concepts/tokens/index.md) and [cross-currency payments](../../../concepts/payment-types/cross-currency-payments.md)
- You could add support for displaying multiple tokens, beyond just XRP
- You could support creating [offers](../../../concepts/tokens/decentralized-exchange/offers.md) in the [decentralized exchange](../../../concepts/tokens/decentralized-exchange/index.md)
- You could add new ways to request payments, such as with QR codes or URIs that open in your wallet.
- You could support better account security including allowing users to set [regular key pairs](../../../concepts/accounts/cryptographic-keys.md#regular-key-pair) or handle [multi-signing](../../../concepts/accounts/multi-signing.md).
- Or you could take your code to production by following the [Building for Production with Vite](https://vitejs.dev/guide/build.html#public-base-path) guide.
{% raw-partial file="/docs/_snippets/common-links.md" /%}

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---
seo:
description: Build a credential issuing microservice with Javascript and Node.js.
---
# Build a Credential Issuing Service
_(Requires the Credentials amendment. {% not-enabled /%})_
This tutorial demonstrates how to build and use a microservice that issues [Credentials](../../../concepts/decentralized-storage/credentials.md) on the XRP Ledger, in the form of a RESTlike API, using the [Express](https://expressjs.com/) framework for Node.js.
## Prerequisites
To complete this tutorial, you should meet the following guidelines:
- You have [Node.js](https://nodejs.org/en/download/) v18 or higher installed.
- You are somewhat familiar with modern JavaScript programming and have completed the [Get Started Using JavaScript tutorial](./get-started.md).
- You have some understanding of the XRP Ledger, its capabilities, and of cryptocurrency in general. Ideally you have completed the [Basic XRPL guide](https://learn.xrpl.org/).
## Setup
First, download the complete sample code for this tutorial from GitHub:
- {% repo-link path="_code-samples/issue-credentials/js/" %}Credential Issuing Service sample code{% /repo-link %}
Then, in the appropriate directory, install the dependencies:
```sh
npm install
```
This should install appropriate versions of Express, xrpl.js and a few other dependencies. You can view all dependencies in the {% repo-link path="_code-samples/issue-credentials/js/package.json" %}`package.json`{% /repo-link %} file.
To use the API that this microservice provides, you also need an HTTP client such as [Postman](https://www.postman.com/downloads/), [RESTED](https://github.com/RESTEDClient/RESTED), or [cURL](https://curl.se/).
## Overview
The Credential Issuer microservice, mostly implemented in `issuer_service.js`, provides a RESTlike API with the following methods:
| Method | Description |
|---|----|
| `POST /credential` | Request that the issuer issue a specific credential to a specific account. |
| `GET /admin/credential` | List all credentials issued by the issuer's address, optionally filtering only for credentials that have or have not been accepted by their subject. |
| `DELETE /admin/credential` | Delete a specific credential from the XRP Ledger, which revokes it. |
{% admonition type="info" name="Note" %}Some of the methods have `/admin` in the path because they are intended to be used by the microservice's administrator. However, the sample code does not implement any authentication.{% /admonition %}
The sample code also contains a simple commmandline interface for a user account to accept a credential issued to it, as `accept_credential.js`.
The other files contain helper code that is used by one or both tools.
## Usage
### 1. Get Accounts
To use the credential issuing service, you need two accounts on the Devnet, where the Credentials amendment is already enabled. Go to the [XRP Faucets page](../../../../resources/dev-tools/xrp-faucets.page.tsx) and select **Devnet**. Then, click the button to Generate credentials, saving the key pair (address and secret), twice. You will use one of these accounts as a **credential issuer** and the other account as the **credential subject** (holder), so make a note of which is which.
### 2. Start Issuer Service
To start the issuer microservice, run the following command from the directory with the sample code:
```sh
node issuer_service.js
```
It should prompt you for your **issuer account** seed. Input the secret key you saved previously and press Enter.
The output should look like the following:
```txt
✔ Issuer account seed:
✅ Starting credential issuer with XRPL address rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3
🔐 Credential issuer service running on port: 3005
```
Double-check that the XRPL address displayed matches the address of the credential issuer keys you saved earlier.
### 3. Request Credential
To request a credential, make a request such as the following:
{% tabs %}
{% tab label="Summary" %}
* HTTP method: `POST`
* URL: `http://localhost:3005/credential`
* Headers:
* `Content-Type: application/json`
* Request Body:
```json
{
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"credential": "TestCredential",
"documents": {
"reason": "please"
}
}
```
{% /tab %}
{% tab label="cURL" %}
```sh
curl -H "Content-Type: application/json" -X POST -d '{"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG", "credential": "TestCredential", "documents": {"reason": "please"}}' http://localhost:3005/credential
```
{% /tab %}
{% /tabs %}
The parameters of the JSON request body should be as follows:
| Field | Type | Required? | Description |
|---|---|---|---|
| `subject` | String - Address | Yes | The XRPL classic address of the subject of the credential. Set this to the address that you generated at the start of this tutorial for the credential holder account. |
| `credential` | String | Yes | The type of credential to issue. The example microservice accepts any string consisting of alphanumeric characters as well as the special characters underscore (`_`), dash (`-`), and period (`.`), with a minimum length of 1 and a maximum length of 64 characters. |
| `documents` | Object | Yes | As a credential issuer, you typically need to verify some confidential information about someone before you issue them a credential. As a placeholder, the sample code checks for a nested field named `reason` that contains the string `please`. |
| `expiration` | String - ISO8601 Datetime | No | The time after which the credential expires, such as `2025-12-31T00:00:00Z`. |
| `uri` | String | No | Optional URI data to store with the credential. This data will become public on the XRP Ledger. If provided, this must be a string with minimum length 1 and max length 256, consisting of only characters that are valid in URIs, which are numbers, letters, and the following special characters: `-._~:/?#[]@!$&'()*+,;=%`. Conventionally, it should link to a Verifiable Credential document as defined by the W3C. |
This microservice immediately issues any credential that the user requests. A successful response from the API uses the HTTP status code `201 Created` and has a response body with the result of submitting the transaction to the XRP Ledger. You can use the `hash` value from the response to look up the transaction using an explorer such as [https://devnet.xrpl.org/](https://devnet.xrpl.org/).
{% admonition type="warning" name="Differences from Production" %}For a real credential issuer, you would probably check the credential type and only issue specific types of credentials, or maybe even just one type. <br><br> If checking the user's documents requires human intervention or takes longer than the amount of time an API request should wait to respond, you would need to store credential requests to some kind of storage, like a SQL database. You might also want to add a separate method for admins (or automated processes) to reject or issue the credential after checking the documents.{% /admonition %}
### 4. List Credentials
To show a list of credentials issued by the issuing account, make the following request:
{% tabs %}
{% tab label="Summary" %}
* HTTP method: `GET`
* URL: `http://localhost:3005/admin/credential`
* Query parameters (optional): Use `?accepted=yes` to filter results to only credentials that the subject has accepted, or `?accepted=no` for credentials the user has not accepted.
{% /tab %}
{% tab label="cURL" %}
```sh
curl http://localhost:3005/admin/credential
```
{% /tab %}
{% /tabs %}
A response could look like the following:
```json
{
"credentials": [
{
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"credential": "TstCredential",
"accepted": true
}
]
}
```
In the response, each entry in the `credentials` array represents a Credential issued by the issuer account and stored in the blockchain. The details should match the request from the previous step, except that the `documents` are omitted because they are not saved on the blockchain.
### 5. Accept Credential
For a credential to be valid, the subject of the credential has to accept it. You can use `accept_credential.js` to do this:
```sh
node accept_credential.js
```
It should prompt you for your **subject account** seed. Input the secret key you saved previously and press Enter.
The script displays a list of Credentials that have been issued to your account and have not been accepted yet. Use the arrrow keys to scroll through the choices in the prompt and select the credential you want to accept, then press Enter. For example:
```text
✔ Subject account seed:
? Accept a credential?
0) No, quit.
1) 'TstzzzCredential' issued by rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3
2) 'Tst9Credential' issued by rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3
❯ 3) 'TCredential1' issued by rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3
4) 'Tst1Credential' issued by rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3
5) 'Tst0Credential' issued by rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3
6) 'Tst6Credential' issued by rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3
```
### 6. Revoke Credential
To revoke an issued credential, make a request such as the following:
{% tabs %}
{% tab label="Summary" %}
* HTTP method: `DELETE`
* URL: `http://localhost:3005/admin/credential`
* Headers:
* `Content-Type: application/json`
* Request Body:
```json
{
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"credential": "TestCredential"
}
```
{% /tab %}
{% tab label="cURL" %}
```sh
curl -H "Content-Type: application/json" -X DELETE -d '{"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG", "credential": "TestCredential"}' http://localhost:3005/admin/credential
```
{% /tab %}
{% /tabs %}
The parameters of the JSON request body should be as follows:
| Field | Type | Required? | Description |
|---|---|---|---|
| `subject` | String - Address | Yes | The XRPL classic address of the subject of the credential to revoke. |
| `credential` | String | Yes | The type of credential to revoke. This must match a credential type previously issued. |
A successful response from the API uses the HTTP status code `200 OK` and has a response body with the result of submitting the transaction to the XRP Ledger. You can use the `hash` value from the response to look up the transaction using an explorer.
## Code Walkthrough
The code for this tutorial is divided among the following files:
| File | Purpose |
|---|---|
| `accept_credential.js` | Commandline interface for a credential subject to look up and accept Credentials. |
| `credential.js` | Provides functions that validate credential input, verify supporting documents, and convert between the microservice’s simplified Credential format and the full XRPL representation of Credentials. |
| `errors.js` | Custom error classes that standardize how the server reports validation errors and XRPL transaction failures. |
| `issuer_service.js` | Defines the microservice as an Express app, including API methods and error handling. |
| `look_up_credentials.js` | A helper function for looking up Credentials tied to an account, including pagination and filtering, used by both the credential issuer and holder. |
### accept_credential.js
This file is meant to be run as a commandline tool so it starts with a [shebang](https://en.wikipedia.org/wiki/Shebang_(Unix)), followed by dependencies grouped by type: external packages (Node.js modules) first, and local modules last.
{% code-snippet file="/_code-samples/issue-credentials/js/accept_credential.js" language="js" before="const XRPL_SERVER =" /%}
It returns a `Wallet` instance in the `initWallet()` function, with the subject account's key pair, using a seed either passed as an environment variable, or input as a password:
{% code-snippet file="/_code-samples/issue-credentials/js/accept_credential.js" language="js" from="const XRPL_SERVER" before="async function main()" /%}
The `main()` function contains the core logic for the script. At the begining of the function it sets up the XRPL client, and calls `initWallet()` to instantiate a `Wallet` object:
{% code-snippet file="/_code-samples/issue-credentials/js/accept_credential.js" language="js" from="async function main()" before="const pendingCredentials =" /%}
It then looks up pending credentials using the `lookUpCredentials(...)` function imported from `look_up_credentials.js`:
{% code-snippet file="/_code-samples/issue-credentials/js/accept_credential.js" language="js" from="const pendingCredentials = " before="const choices" /%}
Next is a text menu that displays each of the unaccepted credentials returned by the lookup, as well as the option to quit:
{% code-snippet file="/_code-samples/issue-credentials/js/accept_credential.js" language="js" from="choices = " before="const chosenCred = " /%}
If the user picked a credential, the code constructs a [CredentialAccept transaction][], signs and submits it, and waits for it to be validated by consensus before displaying the result.
{% code-snippet file="/_code-samples/issue-credentials/js/accept_credential.js" language="js" from="const chosenCred = " before="main().catch" /%}
Finally, the code runs the `main()` function:
{% code-snippet file="/_code-samples/issue-credentials/js/accept_credential.js" language="js" from="main().catch" /%}
### issuer_service.js
This file defines the Express app of the issuer microservice. It opens by importing dependencies, grouped into external packages and local files:
{% code-snippet file="/_code-samples/issue-credentials/js/issuer_service.js" language="js" before="dotenv.config()" /%}
It returns a `Wallet` instance in the `initWallet()` function, with the subject account's key pair, using a seed either passed as an environment variable, or input as a password:
{% code-snippet file="/_code-samples/issue-credentials/js/issuer_service.js" language="js" from="dotenv.config()" before="// Error handling" /%}
A function called `handleAppError(...)` is defined to handle errors thrown by the microservice.
{% code-snippet file="/_code-samples/issue-credentials/js/issuer_service.js" language="js" from="// Error handling" before="async function main()" /%}
The `main()` function contains the core logic for the script. At the begining of the function it sets up the XRPL client, and calls `initWallet()` to instantiate a `Wallet` object:
{% code-snippet file="/_code-samples/issue-credentials/js/issuer_service.js" language="js" from="async function main()" before="// Define Express app" /%}
Next, it creates the Express app:
{% code-snippet file="/_code-samples/issue-credentials/js/issuer_service.js" language="js" from="// Define Express app" before="// POST /credential" /%}
After that come the definitions for the three API methods, starting with `POST /credential`. Users call this method to request a credential from the service. This method parses the request body as JSON and validates it. If this succeeds, it uses the data to fill out a `CredentialCreate` transaction. Finally, it checks the transaction's [result](../../../references/protocol/transactions/transaction-results/index.md) to decide which HTTP response code to use:
{% code-snippet file="/_code-samples/issue-credentials/js/issuer_service.js" language="js" from="// POST /credential" before="// GET /admin/credential" /%}
The next API method is `GET /admin/credential`, which looks up credentials issued by the service. It uses the `lookUpCredentials(...)` method defined in `look_up_credentials.js` to get a list of credentials. Then it calls the `serializeCredential(...)` and `parseCredentialFromXrpl(...)` functions, imported from `credential.js`, to transform each ledger entry from the XRP Ledger format to the simplified representation the microservice uses.
{% code-snippet file="/_code-samples/issue-credentials/js/issuer_service.js" language="js" from="// GET /admin/credential" before="// DELETE /admin/credential" /%}
The final API method, `DELETE /admin/credential`, deletes a Credential from the ledger, revoking it. This again uses functions from `credential.js` to validate user inputs and translate them into XRPL format where necessary. After that, it attempts to look up the Credential in the ledger and returns an error if it doesn't exist. This way, the issuer doesn't have to pay the cost of sending a transaction that would fail. Finally, the method checks the transaction result and sets the HTTP response code accordingly.
{% code-snippet file="/_code-samples/issue-credentials/js/issuer_service.js" language="js" from="// DELETE /admin/credential" before="const PORT = process.env.PORT" /%}
The port for the microservice is set to either an environment variable called `PORT` or to `3000`, and the application listens for connections at the assigned port:
{% code-snippet file="/_code-samples/issue-credentials/js/issuer_service.js" language="js" from="const PORT = process.env.PORT" before="// Start the server" /%}
Finally, the code runs the `main()` function:
{% code-snippet file="/_code-samples/issue-credentials/js/issuer_service.js" language="js" from="// Start the server" before="/**" /%}
### look_up_credentials.js
This file implements lookup of Credentials. Both the issuer code and the subject code use this function to look up their own credentials.
This code performs [pagination using markers](../../../references/http-websocket-apis/api-conventions/markers-and-pagination.md) to get all the results from the ledger. It also filters results based on the issuer/subject account, so that lookup by issuer, for example, doesn't include credentials that someone else issued _to_ the issuer account. Finally, it can optionally check the accepted status of the Credentials and only include ones that are or aren't accepted.
{% code-snippet file="/_code-samples/issue-credentials/js/look_up_credentials.js" language="js" /%}
### credential.js
This file defines a set of helper functions that validate credential related input, verify request data, and convert between the issuer microservice's simplified Credential format and the XRP Ledger object representation. It throws typed errors on invalid input.
The file starts with importing dependencies, grouped into external packages and local files:
{% code-snippet file="/_code-samples/issue-credentials/js/credential.js" before="// Regex constants" language="js" /%}
It then defines regular expression constants that are used further on in the code to validate the credential and uri:
{% code-snippet file="/_code-samples/issue-credentials/js/credential.js" from="// Regex constants" before="/**" language="js" /%}
The function `validateCredentialRequest(...)` checks that the user input meets various requirements. It also parses the user-provided timestamp from a string to a native Javascript Date object if necessary.
{% code-snippet file="/_code-samples/issue-credentials/js/credential.js" from="/**" before="// Convert " language="js" /%}
The `credentialFromXrpl(...)` function converts an XRPL ledger entry into a usable credential object (for example, converting the credential field from hexadecimal to a native string). The API methods that read data from the XRP Ledger use this function so that their output is formatted the same way as user input in the other API methods.
{% code-snippet file="/_code-samples/issue-credentials/js/credential.js" from="// Convert an XRPL ledger" before="// Convert to an object" language="js" /%}
The `credentialToXrpl(...)` function returns an object which is formatted for submitting to the XRP Ledger:
{% code-snippet file="/_code-samples/issue-credentials/js/credential.js" from="Convert to an object" before="export function verifyDocuments" language="js" /%}
Finally, the `verifyDocuments(...)` function checks for an additional field, `documents`. For a realistic credential issuer, you might require the user to provide specific documents in the request body, like a photo of their government-issued ID or a cryptographically signed message from another business, which your code would check. For this tutorial, the check is only a placeholder:
{% code-snippet file="/_code-samples/issue-credentials/js/credential.js" from="export function verifyDocuments" language="js" /%}
### errors.js
This file defines custom error classes used by the credential issuer service to provide consistent error handling and help distinguish between different kinds of failures:
{% code-snippet file="/_code-samples/issue-credentials/js/errors.js" language="js" /%}
## Next Steps
Using this service as a base, you can extend the service with more features, such as:
- Security/authentication to protect API methods from unauthorized use.
- Actually checking user documents to decide if you should issue a credential.
Alternatively, you can use credentials to for various purposes, such as:
- Define a [Permissioned Domain](/docs/concepts/tokens/decentralized-exchange/permissioned-domains) that uses your credentials to grant access to features on the XRP Ledger.
- [Verify credentials](../compliance/verify-credential.md) manually to grant access to services that exist off-ledger.
## See Also
- [Python: Build a Credential Issuing Service](../../python/build-apps/credential-issuing-service.md)
{% raw-partial file="/docs/_snippets/common-links.md" /%}

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@@ -1,173 +0,0 @@
---
html: get-started-using-javascript-library.html
parent: javascript.html
seo:
description: Build an entry-level JavaScript application for querying the XRP Ledger.
top_nav_name: JavaScript
top_nav_grouping: Get Started
labels:
- Development
showcase_icon: assets/img/logos/javascript.svg
---
# Get Started Using JavaScript Library
This tutorial guides you through the basics of building an XRP Ledger-connected application in JavaScript or TypeScript using the [`xrpl.js`](https://github.com/XRPLF/xrpl.js/) client library in either Node.js or web browsers.
The scripts and config files used in this guide are {% repo-link path="_code-samples/get-started/js/" %}available in this website's GitHub Repository{% /repo-link %}.
## Learning Goals
In this tutorial, you'll learn:
* The basic building blocks of XRP Ledger-based applications.
* How to connect to the XRP Ledger using `xrpl.js`.
* How to get an account on the [Testnet](/resources/dev-tools/xrp-faucets) using `xrpl.js`.
* How to use the `xrpl.js` library to look up information about an account on the XRP Ledger.
* How to put these steps together to create a JavaScript app or web-app.
## Requirements
To follow this tutorial, you should have some familiarity with writing code in JavaScript and managing small JavaScript projects. In browsers, any modern web browser with JavaScript support should work fine. In Node.js, **version 14** is recommended. Node.js versions 12 and 16 are also regularly tested.
## Install with npm
Start a new project by creating an empty folder, then move into that folder and use [NPM](https://www.npmjs.com/) to install the latest version of xrpl.js:
```sh
npm install xrpl
```
## Start Building
When you're working with the XRP Ledger, there are a few things you'll need to manage, whether you're adding XRP to your [account](../../../concepts/accounts/index.md), integrating with the [decentralized exchange](../../../concepts/tokens/decentralized-exchange/index.md), or [issuing tokens](../../../concepts/tokens/index.md). This tutorial walks you through basic patterns common to getting started with all of these use cases and provides sample code for implementing them.
Here are some steps you use in many XRP Ledger projects:
1. [Import the library.](#1-import-the-library)
1. [Connect to the XRP Ledger.](#2-connect-to-the-xrp-ledger)
1. [Get an account.](#3-get-account)
1. [Query the XRP Ledger.](#4-query-the-xrp-ledger)
1. [Listen for Events.](#5-listen-for-events)
### 1. Import the Library
How you load `xrpl.js` into your project depends on your development environment:
#### Web Browsers
Add a `<script>` tag such as the following to your HTML:
```html
<script src="https://unpkg.com/xrpl/build/xrpl-latest-min.js"></script>
```
You can load the library from a CDN as in the above example, or download a release and host it on your own website.
This loads the module into the top level as `xrpl`.
#### Node.js
Add the library using [npm](https://www.npmjs.com/). This updates your `package.json` file, or creates a new one if it didn't already exist:
```sh
npm install xrpl
```
Then import the library:
```js
const xrpl = require("xrpl")
```
### 2. Connect to the XRP Ledger
To make queries and submit transactions, you need to connect to the XRP Ledger. To do this with `xrpl.js`, you create an instance of the `Client` class and use the `connect()` method.
{% admonition type="success" name="Tip" %}Many network functions in `xrpl.js` use [Promises](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) to return values asynchronously. The code samples here use the [`async/await` pattern](https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Asynchronous/Async_await) to wait for the actual result of the Promises.{% /admonition %}
{% code-snippet file="/_code-samples/get-started/js/base.js" language="js" /%}
#### Connect to the XRP Ledger Mainnet
The sample code in the previous section shows you how to connect to the Testnet, which is one of the available [parallel networks](../../../concepts/networks-and-servers/parallel-networks.md). When you're ready to move to production, you'll need to connect to the XRP Ledger Mainnet. You can do that in two ways:
* By [installing the core server](../../../infrastructure/installation/index.md) (`rippled`) and running a node yourself. The core server connects to the Mainnet by default, but you can [change the configuration to use Testnet or Devnet](../../../infrastructure/configuration/connect-your-rippled-to-the-xrp-test-net.md). [There are good reasons to run your own core server](../../../concepts/networks-and-servers/index.md#reasons-to-run-your-own-server). If you run your own server, you can connect to it like so:
```
const MY_SERVER = "ws://localhost:6006/"
const client = new xrpl.Client(MY_SERVER)
await client.connect()
```
See the example [core server config file](https://github.com/XRPLF/rippled/blob/c0a0b79d2d483b318ce1d82e526bd53df83a4a2c/cfg/rippled-example.cfg#L1562) for more information about default values.
* By using one of the available [public servers][]:
```
const PUBLIC_SERVER = "wss://xrplcluster.com/"
const client = new xrpl.Client(PUBLIC_SERVER)
await client.connect()
```
### 3. Get Account
The `xrpl.js` library has a `Wallet` class for handling the keys and address of an XRP Ledger account. On Testnet, you can fund a new account like this:
{% code-snippet file="/_code-samples/get-started/js/get-acct-info.js" from="// Create a wallet" before="// Get info" language="js" /%}
If you only want to generate keys, you can create a new `Wallet` instance like this:
```js
const test_wallet = xrpl.Wallet.generate()
```
Or, if you already have a seed encoded in [base58][], you can make a `Wallet` instance from it like this:
```js
const test_wallet = xrpl.Wallet.fromSeed("sn3nxiW7v8KXzPzAqzyHXbSSKNuN9") // Test secret; don't use for real
```
### 4. Query the XRP Ledger
Use the Client's `request()` method to access the XRP Ledger's [WebSocket API](../../../references/http-websocket-apis/api-conventions/request-formatting.md). For example:
{% code-snippet file="/_code-samples/get-started/js/get-acct-info.js" from="// Get info" before="// Listen to ledger close events" language="js" /%}
### 5. Listen for Events
You can set up handlers for various types of events in `xrpl.js`, such as whenever the XRP Ledger's [consensus process](../../../concepts/consensus-protocol/index.md) produces a new [ledger version](../../../concepts/ledgers/index.md). To do that, first call the [subscribe method][] to get the type of events you want, then attach an event handler using the `on(eventType, callback)` method of the client.
{% code-snippet file="/_code-samples/get-started/js/get-acct-info.js" from="// Listen to ledger close events" before="// Disconnect when done" language="js" /%}
## Keep on Building
Now that you know how to use `xrpl.js` to connect to the XRP Ledger, get an account, and look up information about it, you can also:
* [Send XRP](../../how-tos/send-xrp.md).
* [Issue a Fungible Token](../../how-tos/use-tokens/issue-a-fungible-token.md)
* [Set up secure signing](../../../concepts/transactions/secure-signing.md) for your account.
## See Also
- **Concepts:**
- [XRP Ledger Overview](/about/)
- [Client Libraries](../../../references/client-libraries.md)
- **Tutorials:**
- [Send XRP](../../how-tos/send-xrp.md)
- **References:**
- [`xrpl.js` Reference](https://js.xrpl.org/)
- [Public API Methods](../../../references/http-websocket-apis/public-api-methods/index.md)
- [API Conventions](../../../references/http-websocket-apis/api-conventions/index.md)
- [base58 Encodings](../../../references/protocol/data-types/base58-encodings.md)
- [Transaction Formats](../../../references/protocol/transactions/index.md)
{% raw-partial file="/docs/_snippets/common-links.md" /%}

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---
seo:
description: Create a permissioned domain to restrict access to financial services that meet compliance requirements.
labels:
- Decentralized Finance
- Permissioned Domains
---
# Create Permissioned Domains
Permissioned domains are controlled environments within the broader ecosystem of the XRP Ledger blockchain. Domains restrict access to other features such as Permissioned DEXes and Lending Protocols, only allowing access to them for accounts with specific credentials.
This example shows how to:
1. Issue a credential to an account.
2. Create a permissioned domain with the issued credential.
3. Delete the permissioned domain.
[![Create Permissioned Domain Test Harness](/docs/img/create-permissioned-domain-1.png)](/docs/img/create-permissioned-domain-1.png)
Download the [Modular Tutorials](https://github.com/XRPLF/xrpl-dev-portal/tree/master/_code-samples/modular-tutorials/) folder.
{% admonition type="info" name="Note" %}
Without the Modular Tutorial Samples, you will not be able to try the examples that follow.
{% /admonition %}
## Get Accounts
To get test accounts:
1. Open `create-permissioned-domains.html` in a browser.
2. Get test accounts.
- If you copied the gathered information from another tutorial:
1. Paste the gathered information to the **Result** field.
2. Click **Distribute Account Info**.
- If you have an existing account seed:
1. Paste the account seed to the **Account 1 Seed** or **Account 2 Seed** field.
2. Click **Get Account 1 from Seed** or **Get Account 2 from Seed**.
- If you do not have existing accounts:
1. Click **Get New Account 1**.
2. Click **Get New Account 2**.
[![Created Accounts](/docs/img/create-permissioned-domain-2.png)](/docs/img/create-permissioned-domain-2.png)
## Issue a Credential
1. Click the **Account 1** radial button. This account will be the credential issuer.
2. Copy the account 2 address into **Subject**.
3. Enter a **Credential Type**. For example, _KYC_.
4. Click **Create Credential**.
[![Created Credential](/docs/img/create-permissioned-domain-3.png)](/docs/img/create-permissioned-domain-3.png)
## Create a Permissioned Domain
1. Click **Create Permissioned Domain**.
2. Copy the _LedgerIndex_ value from the metadata response.
3. (Optional) Update the permissioned domain with a different credential.
1. Change the **Credential Type**.
2. Click **Create Credential**.
3. Copy the _LedgerIndex_ value into **DomainID**.
4. Click **Create Permissioned Domain**.
[![Created Domain](/docs/img/create-permissioned-domain-4.png)](/docs/img/create-permissioned-domain-4.png)
## Delete a Permissioned Domain
1. Copy the _LedgerIndex_ value into **DomainID**.
2. Click **Delete Permissioned Domain**.
[![Deleted Domain](/docs/img/create-permissioned-domain-5.png)](/docs/img/create-permissioned-domain-5.png)
# Code Walkthrough
## credential-manager.js
### Create Credential
Define a function that issues a credential to a subject and connects to the XRP Ledger.
{% code-snippet file="/_code-samples/modular-tutorials/credential-manager.js" language="js" from="// Create credential function" before="// Gather transaction info" /%}
Gather the issuer information, subject, and credential type. Convert the credential type value to a hex string if not already in hex. Wrap the code in a `try-catch` block to handle errors.
{% code-snippet file="/_code-samples/modular-tutorials/credential-manager.js" language="js" from="// Gather transaction info" before="// Submit transaction" /%}
Submit the `CredentialCreate` transaction and report the results. Parse the metadata response to return only relevant credential info.
{% code-snippet file="/_code-samples/modular-tutorials/credential-manager.js" language="js" from="// Submit transaction" /%}
## permissioned-domain-manager.js
### Create Permissioned Domain
Define a function that creates a permissioned domain and connects to the XRP Ledger.
{% code-snippet file="/_code-samples/modular-tutorials/permissioned-domain-manager.js" language="js" from="/// Create permissioned domain" before="// Gather transaction info" /%}
Gather issuer information, credential type, and domain ID. Format the transaction depending on if the optional domain ID field is included. Wrap the code in a `try-catch` block to handle errors.
{% code-snippet file="/_code-samples/modular-tutorials/permissioned-domain-manager.js" language="js" from="// Gather transaction info" before="// Submit transaction" /%}
Submit the `PermissionedDomainSet` transaction and report the results. The metadata is formed differently if a domain ID is included; parse the response accordingly.
{% code-snippet file="/_code-samples/modular-tutorials/permissioned-domain-manager.js" language="js" from="// Submit transaction" before="// End create permissioned domain" /%}
### Delete Permissioned Domain
Define a function to delete a permissioned domain and connect to the XRP Ledger.
{% code-snippet file="/_code-samples/modular-tutorials/permissioned-domain-manager.js" language="js" from="// Delete permissioned domain" before="// Get delete domain transaction info" /%}
Gather account information and domain ID values. Wrap the code in a `try-catch` block to handle errors.
{% code-snippet file="/_code-samples/modular-tutorials/permissioned-domain-manager.js" language="js" from="// Get delete domain transaction info" before="// Submit delete domain transaction" /%}
Submit the `PermissionedDomainDelete` transaction and report the results.
{% code-snippet file="/_code-samples/modular-tutorials/permissioned-domain-manager.js" language="js" from="// Submit delete domain transaction" /%}

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@@ -1,320 +0,0 @@
---
seo:
description: Verify that an account holds a valid credential on the XRP Ledger.
labels:
- Credentials
---
# Verify Credentials in Javascript
This tutorial describes how to verify that an account holds a valid [credential](/docs/concepts/decentralized-storage/credentials) on the XRP Ledger, which has different use cases depending on the type of credential and the meaning behind it. A few possible reasons to verify a credential include:
- Confirming that a recipient has passed a background check before sending a payment.
- Checking a person's professional certifications, after verifying their identity with a [DID](/docs/concepts/decentralized-storage/decentralized-identifiers).
- Displaying a player's achievements in a blockchain-connected game.
This tutorial uses sample code in Javascript using the [xrpl-js library](../index.md).
## Prerequisites
- You must have Node.js installed and know how to run Javascript code from the command line. Node.js v18 is required for xrpl.js.
- You should have a basic understanding of the XRP Ledger.
- The credential you want to verify should exist in the ledger already, and you should know the addresses of both the issuer and the holder, as well as the official credential type you want to check.
- For sample code showing how to create credentials, see [Build a Credential Issuing Service](../build-apps/credential-issuing-service.md).
## Setup
First, download the complete sample code for this tutorial from GitHub:
- {% repo-link path="_code-samples/verify-credential/js/" %}Verify Credential sample code{% /repo-link %}
Then, in the appropriate directory, install dependencies:
```sh
npm install
```
This installs the appropriate version of the `xrpl.js` library and a few other dependencies. You can view all dependencies in the {% repo-link path="_code-samples/verify-credentials/js/package.json" %}`package.json`{% /repo-link %} file.
## Overview
The Verify Credential sample code consists of one file, `verify_credential.js`, and contains two main parts:
1. A function, `verifyCredential(...)` which can be called with appropriate arguments to verify that a credential exists and is valid. This function can be imported into other code to be used as part of a larger application.
2. A commandline utility that can be used to verify any credential.
## Usage
To test that you have the code installed and working properly, you can run the commandline utility with no arguments to check the existence of a default credential on Devnet, such as:
```sh
node verify_credential.js
```
If all goes well, you should see output such as the following:
```text
info: Encoded credential_type as hex: 5465737443726564656E7469616C
info: Looking up credential...
info: {
"command": "ledger_entry",
"credential": {
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
"credential_type": "5465737443726564656E7469616C"
},
"ledger_index": "validated"
}
info: Found credential:
info: {
"CredentialType": "5465737443726564656E7469616C",
"Flags": 65536,
"Issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
"IssuerNode": "0",
"LedgerEntryType": "Credential",
"PreviousTxnID": "B078C70D17820069BDF913146F9908A209B4E10794857A3E474F4C9C5A35CA6A",
"PreviousTxnLgrSeq": 1768183,
"Subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"SubjectNode": "0",
"index": "F2ACB7292C4F4ACB18010251F1653934DC17F06AA5BDE7F484F65B5A648D70CB"
}
info: Credential is valid.
```
If the code reports that the credential was not found when called with no arguments, it's possible that the example credential has been deleted or the Devnet has been reset. If you have another credential you can verify, you can provide the details as commandline arguments. For example:
```sh
node verify_credential.js rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3 rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG TestCredential
```
A full usage statement is available with the `-h` flag.
### Other Examples
The following examples show other possible scenarios. The data for these examples may or may not still be present in Devnet. For example, anyone can delete an expired credential.
{% tabs %}
{% tab label="Valid with Expiration" %}
```text
$ ./verify_credential.js rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3 rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG TCredential777
info: Encoded credential_type as hex: 5443726564656E7469616C373737
info: Looking up credential...
info: {
"command": "ledger_entry",
"credential": {
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
"credential_type": "5443726564656E7469616C373737"
},
"ledger_index": "validated"
}
info: Found credential:
info: {
"CredentialType": "5443726564656E7469616C373737",
"Expiration": 798647105,
"Flags": 65536,
"Issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
"IssuerNode": "0",
"LedgerEntryType": "Credential",
"PreviousTxnID": "D32F66D1446C810BF4E6310E21111C0CE027140292347F0C7A73322F08C07D7E",
"PreviousTxnLgrSeq": 2163057,
"Subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"SubjectNode": "0",
"URI": "746573745F757269",
"index": "6E2AF1756C22BF7DC3AA47AD303C985026585B54425E7FACFAD6CD1867DD39C2"
}
info: Credential has expiration: 2025-04-22T14:25:05.000Z
info: Looking up validated ledger to check for expiration.
info: Most recent validated ledger is: 2025-04-22T13:47:30.000Z
info: Credential is valid.
```
{% /tab %}
{% tab label="Expired" %}
```text
$ ./verify_credential.js rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3 rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG TCredential777
info: Encoded credential_type as hex: 5443726564656E7469616C373737
info: Looking up credential...
info: {
"command": "ledger_entry",
"credential": {
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
"credential_type": "5443726564656E7469616C373737"
},
"ledger_index": "validated"
}
info: Found credential:
info: {
"CredentialType": "5443726564656E7469616C373737",
"Expiration": 798647105,
"Flags": 65536,
"Issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
"IssuerNode": "0",
"LedgerEntryType": "Credential",
"PreviousTxnID": "D32F66D1446C810BF4E6310E21111C0CE027140292347F0C7A73322F08C07D7E",
"PreviousTxnLgrSeq": 2163057,
"Subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"SubjectNode": "0",
"URI": "746573745F757269",
"index": "6E2AF1756C22BF7DC3AA47AD303C985026585B54425E7FACFAD6CD1867DD39C2"
}
info: Credential has expiration: 2025-04-22T14:25:05.000Z
info: Looking up validated ledger to check for expiration.
info: Most recent validated ledger is: 2025-04-22T14:40:00.000Z
info: Credential is expired.
```
{% /tab %}
{% tab label="Unaccepted" %}
```text
$ ./verify_credential.js rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3 rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG Tst9Credential
info: Encoded credential_type as hex: 5473743943726564656E7469616C
info: Looking up credential...
info: {
"command": "ledger_entry",
"credential": {
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
"credential_type": "5473743943726564656E7469616C"
},
"ledger_index": "validated"
}
info: Found credential:
info: {
"CredentialType": "5473743943726564656E7469616C",
"Expiration": 797007605,
"Flags": 0,
"Issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
"IssuerNode": "0",
"LedgerEntryType": "Credential",
"PreviousTxnID": "A7A5F2AF66222B7ECDBC005477BDDCE35E1460FC53339A7800CBDE79DBBB6FE4",
"PreviousTxnLgrSeq": 1633091,
"Subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"SubjectNode": "0",
"URI": "746573745F757269",
"index": "4282469903F9046C8E559447CB1B17A18362E2AFC04399BB7516EFB0B1413EAB"
}
info: Credential is not accepted.
```
{% /tab %}
{% tab label="Hexadecimal Credential Type" %}
```text
$ ./verify_credential.js rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3 rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG 5473743343726564656E7469616C -b
info: Looking up credential...
info: {
"command": "ledger_entry",
"credential": {
"subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
"credential_type": "5473743343726564656E7469616C"
},
"ledger_index": "validated"
}
info: Found credential:
info: {
"CredentialType": "5473743343726564656E7469616C",
"Flags": 65536,
"Issuer": "rPLY4DWhB4VA7PPZ8nvZLhShXeVZqeKif3",
"IssuerNode": "0",
"LedgerEntryType": "Credential",
"PreviousTxnID": "062DA0586A57A32220785159D98F5206A14C4B98F5A7D8A9BCDB6836E33C45FE",
"PreviousTxnLgrSeq": 1768019,
"Subject": "rBqPPjAW6ubfFdmwERgajvgP5LtM4iQSQG",
"SubjectNode": "0",
"URI": "746573745F757269",
"index": "8548D8DC544153044D17E38499F8CB4E00E40A93085FD979AB8B949806668843"
}
info: Credential is valid.
```
{% /tab %}
{% /tabs %}
## Code Walkthrough
### 1. Initial setup
The `verify_credential.js` file implements the code for this tutorial.
This file can be run as a commandline tool, so it starts with a [shebang](https://en.wikipedia.org/wiki/Shebang_(Unix)). Then it imports the relevant dependencies, including the specific parts of the `xrpl.js` library:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" before="// Set up logging" /%}
The next section of the code sets the default log level for messages that might be written to the console through the utility:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Set up logging" before="// Define an error to throw" /%}
Then it defines a type of exception to throw if something goes wrong when connecting to the XRP Ledger:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Define an error to throw" before="const CREDENTIAL" /%}
Finally, a regular expression to validate the credential format and the [lsfAccepted](../../../references/protocol/ledger-data/ledger-entry-types/credential.md#credential-flags) flag are defined as constants for use further on in the code.
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="const CREDENTIAL" before="async function verifyCredential" /%}
### 2. verifyCredential function
The `verifyCredential(...)` function performs the main work for this tutorial. The function definition and comments define the parameters:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="async function verifyCredential" before="// Encode credentialType as uppercase hex" /%}
The XRP Ledger APIs require the credential type to be hexadecimal, so it converts the user input if necessary:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Encode credentialType as uppercase hex" before="// Perform XRPL lookup" /%}
Next, it calls the [ledger_entry method](/docs/references/http-websocket-apis/public-api-methods/ledger-methods/ledger_entry#get-credential-entry) to look up the requested Credential ledger entry:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Perform XRPL lookup" before="// Check if the credential has been accepted" /%}
If it succeeds in finding the credential, the function continues by checking that the credential has been accepted by its holder. Since anyone can issue a credential to anyone else, a credential is only considered valid if its subject has accepted it.
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="Check if the credential has been accepted" before="// Confirm that the credential is not expired" /%}
Then, if the credential has an expiration time, the function checks that the credential is not expired. If the credential has no expiration, this step can be skipped. A credential is officially considered expired if its expiration time is before the [official close time](/docs/concepts/ledgers/ledger-close-times) of the most recently validated ledger. This is more universal than comparing the expiration to your own local clock. Thus, the code uses the [ledger method][] to look up the most recently validated ledger:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Confirm that the credential is not expired" before="// Credential has passed all checks" /%}
If none of the checks up to this point have returned a `false` value, then the credential must be valid. This concludes the `verifyCredential(...)` function:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Credential has passed all checks" before="// Commandline usage" /%}
### 3. Commandline interface
This file also implements a commandline utility which runs when the file is executed directly as a Node.js script. Some variables, such as the set of available networks, are only needed for this mode:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Commandline usage" before="// Parse arguments" /%}
Then it uses the [commander package](https://www.npmjs.com/package/commander) to define and parse the arguments that the user can pass from the commandline:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Parse arguments" before="// Call verify_credential" /%}
After parsing the commandline args, it sets the appropriate values and passes them to `verifyCredential(...)` to perform the credential verification:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Call verify_credential" before="// Return a nonzero exit code" /%}
It returns a nonzero exit code if this credential was not verified. This can be useful for shell scripts:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="// Return a nonzero exit code" before="main().catch" /%}
Finally, the code runs the `main()` function:
{% code-snippet file="/_code-samples/verify-credential/js/verify_credential.js" language="js" from="main().catch" /%}
## Next Steps
Now that you know how to use `xrpl.js` to verify credentials, you can try building this or related steps together into a bigger project. For example:
- Incorporate credential verification into a [wallet application](../build-apps/build-a-desktop-wallet-in-javascript.md).
- Issue your own credentials with a [credential issuing service](../build-apps/credential-issuing-service.md).
## See Also
- [Verify Credentials in Python](../../python/compliance/verify-credential.md)
{% raw-partial file="/docs/_snippets/common-links.md" /%}