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Example of WebUSB implementation in a JS App

This is the renderer.js file for Google’s Carlo application.

It uses the WebUSB package and the BTC Package (see more in the App Protocol section).

import "babel-polyfill";
import TransportWebUSB from "@ledgerhq/hw-transport-webusb";
import AppBtc from "@ledgerhq/hw-app-btc";

const initial =
  "<h1>Connect your Ledger and open Bitcoin app. Click anywhere to start...</h1>";

const $main = document.getElementById("main");
$main.innerHTML = initial;

document.body.addEventListener("click", async () => {
  $main.innerHTML = initial;
  try {
    const transport = await TransportWebUSB.create();
    const appBtc = new AppBtc(transport);
    const { bitcoinAddress } = await appBtc.getWalletPublicKey(
    const h2 = document.createElement("h2");
    h2.textContent = bitcoinAddress;
    $main.innerHTML = "<h1>Your first Bitcoin address:</h1>";
    await appBtc.getWalletPublicKey("44'/0'/0'/0/0", true);
  } catch (e) {
    const $err = document.createElement("code");
    $err.style.color = "#f66";
    $err.textContent = String(e.message || e);

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