docs: change examples in docs to use for..of and async/await (#15196)

docs/api/desktop-capturer.md

@@ -12,24 +12,28 @@ title is `Electron`:
 // In the renderer process.
 const { desktopCapturer } = require('electron')
 
-desktopCapturer.getSources({ types: ['window', 'screen'] }, (error, sources) => {
+desktopCapturer.getSources({ types: ['window', 'screen'] }, async (error, sources) => {
   if (error) throw error
-  for (let i = 0; i < sources.length; ++i) {
+  for (const source of sources) {
-    if (sources[i].name === 'Electron') {
+    if (source.name === 'Electron') {
-      navigator.mediaDevices.getUserMedia({
+      try {
+        const stream = await navigator.mediaDevices.getUserMedia({
           audio: false,
           video: {
             mandatory: {
               chromeMediaSource: 'desktop',
-            chromeMediaSourceId: sources[i].id,
+              chromeMediaSourceId: source.id,
               minWidth: 1280,
               maxWidth: 1280,
               minHeight: 720,
               maxHeight: 720
             }
           }
-      }).then((stream) => handleStream(stream))
+        })
-        .catch((e) => handleError(e))
+        handleStream(stream)
+      } catch (e) {
+        handleError(e)
+      }
       return
     }
   }

docs/tutorial/using-selenium-and-webdriver.md

@@ -20,32 +20,33 @@ $ npm install --save-dev spectron
 
 ```javascript
 // A simple test to verify a visible window is opened with a title
-var Application = require('spectron').Application
+const Application = require('spectron').Application
-var assert = require('assert')
+const assert = require('assert')
 
-var app = new Application({
+const myApp = new Application({
   path: '/Applications/MyApp.app/Contents/MacOS/MyApp'
 })
 
-app.start().then(function () {
+const verifyWindowIsVisibleWithTitle = async (app) => {
+  await app.start()
+  try {
     // Check if the window is visible
-  return app.browserWindow.isVisible()
+    const isVisible = await app.browserWindow.isVisible()
-}).then(function (isVisible) {
     // Verify the window is visible
     assert.strictEqual(isVisible, true)
-}).then(function () {
     // Get the window's title
-  return app.client.getTitle()
+    const title = await app.client.getTitle()
-}).then(function (title) {
     // Verify the window's title
     assert.strictEqual(title, 'My App')
-}).catch(function (error) {
+  } catch (error) {
     // Log any failures
     console.error('Test failed', error.message)
-}).then(function () {
+  }
   // Stop the application
-  return app.stop()
+  await app.stop()
-})
+}
+
+verifyWindowIsVisibleWithTitle(myApp)
 ```
 
 ## Setting up with WebDriverJs