xrpl-dev-portal/_code-samples/build-a-desktop-wallet/js/1-ledger-index/index.js

const { app, BrowserWindow } = require('electron')

const path = require('path')
const xrpl = require("xrpl")

const TESTNET_URL = "wss://s.altnet.rippletest.net:51233"

/**
 * This function creates a WebService client, which connects to the XRPL and fetches the latest ledger index.
 *
 * @returns {Promise<number>}
 */
const getValidatedLedgerIndex = async () => {
    const client = new xrpl.Client(TESTNET_URL)

    await client.connect()

    // Reference: https://xrpl.org/ledger.html#ledger
    const ledgerRequest = {
        "command": "ledger",
        "ledger_index": "validated"
    }

    const ledgerResponse = await client.request(ledgerRequest)

    await client.disconnect()

    return ledgerResponse.result.ledger_index
}

/**
 * This is our main function, it creates our application window, preloads the code we will need to communicate
 * between the renderer Process and the main Process, loads a layout and performs the main logic
 */
const createWindow = () => {

    // Creates the application window
    const appWindow = new BrowserWindow({
        width: 1024,
        height: 768,
        webPreferences: {
            preload: path.join(__dirname, 'view', 'preload.js'),
        },
    })

    // Loads a layout
    appWindow.loadFile(path.join(__dirname, 'view', 'template.html'))

    return appWindow
}

// Here we have to wait for the application to signal that it is ready
// to execute our code. In this case we create a main window, query
// the ledger for its latest index and submit the result to the main
// window where it will be displayed
app.whenReady().then(() => {

    const appWindow = createWindow()

    getValidatedLedgerIndex().then((value) => {
        appWindow.webContents.send('update-ledger-index', value)
    })
})