Add Permission Delegation sample code

_code-samples/delegate-permissions/README.md

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+# Delegate Permissions
+
+Delegate permissions to another account, so that the account can send transactions on your behalf.

_code-samples/delegate-permissions/js/README.md

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+# Delegate Permissions (JavaScript) Sample Code
+
+These code samples demonstrate how to delegate permissions to another account and how to send an a transaction as a delegate, using xrpl.js 4.3 in Node.js.
+
+## Usage
+
+1. First, install dependencies.
+
+    ```sh
+    npm i
+    ```
+
+2. Go to the [XRP Faucet](https://xrpl.org/resources/dev-tools/xrp-faucets) and generate a **Devnet** account to be your delegate account.
+
+3. Edit `delegate-permisions.js` and change the following line to use the address you got from the faucet:
+
+    ```js
+        const delegate_address = "r9GAKojMTyexqvy8DXFWYq63Mod5k5wnkT"
+    ```
+
+4. Run `delegate-permissions.js`.
+
+    ```sh
+    node delegate-permissions.js
+    ```
+
+    If it runs successfully, it should output several things including "Delegate successfully set." followed by an [account_objects API method](https://xrpl.org/docs/references/http-websocket-apis/public-api-methods/account-methods/account_objects) response showing the delegate permissions.
+
+    Take note of the `account` address in this output. That's the address of the delegating account.
+
+5. Run `use-delegate-permissions.js` and provide both the delegating account's address (from the previous step's output) and the delegate's secret key (from the devnet faucet earlier).
+
+    If it runs successfully, it should output various things ending in the following:
+    
+    ```text
+    Transaction successful.
+    Domain is example.com
+    ```

_code-samples/delegate-permissions/js/delegate-permissions.js

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+const xrpl = require('xrpl')
+
+async function main() {
+    const client = new xrpl.Client("wss://s.devnet.rippletest.net:51233")
+    await client.connect()
+
+    console.log("Funding new wallet from faucet...")
+    const { wallet } = await client.fundWallet()
+
+    // Define the transaction
+    const delegate_address = "r9GAKojMTyexqvy8DXFWYq63Mod5k5wnkT"
+    const delegateset = {
+        "TransactionType": "DelegateSet",
+        "Account": wallet.address,
+        "Authorize": delegate_address,
+        "Permissions": [
+            {
+                "Permission": {
+                    "PermissionValue": "AccountDomainSet"
+                }
+            }
+        ]
+    }
+
+    // Prepare, sign, and submit the transaction
+    const prepared = await client.autofill(delegateset)
+    const signed = wallet.sign(prepared)
+    const result = await client.submitAndWait(signed.tx_blob)
+
+    // Check transaction results
+    console.log(result)
+    if (result.result.meta.TransactionResult === "tesSUCCESS") {
+        console.log("Delegate successfully set.")
+    }
+
+    // Confirm presence of Delegate ledger entry using account_objects
+    response = await client.request({
+        "command": "account_objects",
+        "account": wallet.address,
+        "type": "delegate",
+        "ledger_index": "validated"
+    })
+    console.log(JSON.stringify(response, null, 2))
+
+    client.disconnect()
+}
+
+main()

_code-samples/delegate-permissions/js/package.json

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+{
+  "dependencies": {
+    "xrpl": "^4.3.0"
+  }
+}

_code-samples/delegate-permissions/js/use-delegated-permissions.js

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+const xrpl = require('xrpl')
+const readline = require('readline').createInterface({
+  input: process.stdin,
+  output: process.stdout
+})
+const { stringToHex, hexToString } = require('@xrplf/isomorphic/utils')
+
+// Set delegating account and delegate from user input
+readline.question(`Address of delegating account? `, async function(from_address) {
+  readline.question(`Delegate's secret key? `, async function(secret) {
+    const client = new xrpl.Client("wss://s.devnet.rippletest.net:51233")
+    await client.connect()
+
+    const delegate_wallet = xrpl.Wallet.fromSeed(secret)
+    console.log(`Using delegate address ${delegate_wallet.address}`)
+
+    // Check which permissions the delegate has been granted, if any
+    response = await client.request({
+        "command": "account_objects",
+        "account": from_address,
+        "type": "delegate",
+        "ledger_index": "validated"
+    })
+    let found_match = false
+    for (delegate_entry of response.result.account_objects) {
+      if (delegate_entry.Account == from_address && delegate_entry.Authorize == delegate_wallet.address) {
+        found_match = true
+        console.log("Delegate has the following permissions:")
+        for (perm of delegate_entry.Permissions) {
+          console.log(perm.Permission.PermissionValue)
+        }
+        break
+      }
+    }
+    if (!found_match) {
+      console.warn("Delegate appears not to have any permissions granted by delegating account.")
+      console.warn("Did you run delegate-permissions.js first with your delegate address?")
+      return
+    }
+
+    // Use the AccountDomainSet granular permission to set the "Domain" field
+    // of the delegating account
+    const set_domain_example = {
+      "TransactionType": "AccountSet",
+      "Account": from_address,
+      "Delegate": delegate_wallet.address,
+      "Domain": stringToHex("example.com")
+    }
+
+    // Prepare, sign, and submit the transaction
+    const prepared = await client.autofill(set_domain_example)
+    const signed = delegate_wallet.sign(prepared)
+    console.log("Submitting transaction:")
+    console.log(JSON.stringify(signed, null, 2))
+    const result = await client.submitAndWait(signed.tx_blob)
+
+    // Check transaction results and disconnect
+    console.log(result)
+    if (result.result.meta.TransactionResult === "tesSUCCESS") {
+      console.log("Transaction successful.")
+    }
+
+    // Confirm that the account's Domain field has been set as expected
+    const account_info_resp = await client.request({
+      "command": "account_info",
+      "account": from_address,
+      "ledger_index": "validated"
+    })
+    const domain_str = hexToString(account_info_resp.result.account_data.Domain)
+    console.log(`Domain is ${domain_str}`)
+
+    client.disconnect()
+  })
+})