docs: change variable declaration to modern syntax (#2692)

Issue #2544

docs/tutorials/a11y.md

@@ -38,7 +38,7 @@ will need to change the aria-label as well.
 
 ```js
 this.eventManager.listen(this.button_, 'click', () => {
-  let nextManifest = /* Your logic to pick the next video to be played */
+  const nextManifest = /* Your logic to pick the next video to be played */
     myapp.getNextManifest();
 
   this.player.load(nextManifest);

docs/tutorials/ad_monetization.md

@@ -58,15 +58,15 @@ const video = document.getElementById('video');
 const ui = video['ui'];
 // If you're using a non-UI build, this is the div you'll need to create
 // for your layout.
-var container = video.ui.getControls().getControlsContainer();
+const container = video.ui.getControls().getControlsContainer();
 adManager.initClientSide(container, video);
 ```
 
 With the client side logic initialized, you can request ads at any time during
 the presentation.
 
 ```js
-var adsRequest = new google.ima.AdsRequest();
+const adsRequest = new google.ima.AdsRequest();
 // Your ad tag url should go here. We are using a sample ad tag from the
 // IMA HTML5 SDK implementation guide for this tutorial.
 adsRequest.adTagUrl = 'https://pubads.g.doubleclick.net/gampad/ads?' +
@@ -100,7 +100,7 @@ const video = document.getElementById('video');
 const ui = video['ui'];
 // If you're using a non-UI build, this is the div you'll need to create
 // for your layout.
-var container = video.ui.getControls().getServerSideAdContainer();
+const container = video.ui.getControls().getServerSideAdContainer();
 adManager.initServerSide(container, video);
 ```
 
@@ -110,7 +110,7 @@ dynamically inserted ads.
 Requesting a VOD stream:
 
 ```js
-var streamRequest = new google.ima.dai.api.VODStreamRequest();
+const streamRequest = new google.ima.dai.api.VODStreamRequest();
 // Your stream information will go here. We are using IMA's sample stream info
 // in this tutorial.
 streamRequest.contentSourceId = '2528370';
@@ -129,7 +129,7 @@ See [google.ima.dai.api.VODStreamRequest][] for details on the request object.
 Requesting a LIVE stream:
 
 ```js
-var streamRequest = new google.ima.dai.api.LiveStreamRequest();
+const streamRequest = new google.ima.dai.api.LiveStreamRequest();
 // Your stream information will go here. We are using IMA's sample stream info
 // in this tutorial.
 streamRequest.assetKey = 'sN_IYUG8STe1ZzhIIE_ksA';

docs/tutorials/basic-usage.md

@@ -32,7 +32,7 @@ Basic usage of Shaka Player is very easy:
 ```js
 // myapp.js
 
-var manifestUri =
+const manifestUri =
     'https://storage.googleapis.com/shaka-demo-assets/angel-one/dash.mpd';
 
 function initApp() {
@@ -51,8 +51,8 @@ function initApp() {
 
 function initPlayer() {
   // Create a Player instance.
-  var video = document.getElementById('video');
-  var player = new shaka.Player(video);
+  const video = document.getElementById('video');
+  const player = new shaka.Player(video);
 
   // Attach player to the window to make it easy to access in the JS console.
   window.player = player;

docs/tutorials/debugging.md

@@ -9,7 +9,7 @@ and make a bad change.
 First, let's change `manifestUri` by removing the last letter.
 
 ```js
-var manifestUri =
+const manifestUri =
     'https://storage.googleapis.com/shaka-demo-assets/angel-one/dash.mp';
 ```
 

docs/tutorials/license-server-auth.md

@@ -15,9 +15,9 @@ To start, we're going to use the code from {@tutorial basic-usage}, but use this
 manifest and license server:
 
 ```js
-var manifestUri =
+const manifestUri =
     'https://storage.googleapis.com/shaka-demo-assets/sintel-widevine/dash.mpd';
-var licenseServer = 'https://cwip-shaka-proxy.appspot.com/no_auth';
+const licenseServer = 'https://cwip-shaka-proxy.appspot.com/no_auth';
 ```
 
 We'll also need to configure the player to use this license server before it
@@ -44,7 +44,7 @@ Since the endpoint is `/no_auth`, this should play without authentication.
 First, we'll try authentication using headers.  Change the license server to:
 
 ```js
-var licenseServer = 'https://cwip-shaka-proxy.appspot.com/header_auth';
+const licenseServer = 'https://cwip-shaka-proxy.appspot.com/header_auth';
 ```
 
 This endpoint requires a specific header value to deliver a license.  If you
@@ -79,7 +79,7 @@ Next, we'll try authentication using URL parameters.  Change the license server
 to:
 
 ```js
-var licenseServer = 'https://cwip-shaka-proxy.appspot.com/param_auth';
+const licenseServer = 'https://cwip-shaka-proxy.appspot.com/param_auth';
 ```
 
 This endpoint requires a specific URL parameter to deliver a license.  If you
@@ -110,7 +110,7 @@ Finally, let's try using cookies for authentication.  Change the license server
 to:
 
 ```js
-var licenseServer = 'https://cwip-shaka-proxy.appspot.com/cookie_auth';
+const licenseServer = 'https://cwip-shaka-proxy.appspot.com/cookie_auth';
 ```
 
 This endpoint requires a specific cookie to deliver a license.  If you try to
@@ -161,7 +161,7 @@ pointing your browser to the server's [delete\_cookie][] page.  Then set your
 license server back to:
 
 ```js
-var licenseServer = 'https://cwip-shaka-proxy.appspot.com/no_auth';
+const licenseServer = 'https://cwip-shaka-proxy.appspot.com/no_auth';
 ```
 
 Since `allowCrossSiteCredentials` is `true` and that endpoint doesn't
@@ -194,9 +194,9 @@ of an asynchronous filter.
 To start, change the license server and add two additional variables:
 
 ```js
-var licenseServer = 'https://cwip-shaka-proxy.appspot.com/header_auth';
-var authTokenServer = 'https://cwip-shaka-proxy.appspot.com/get_auth_token';
-var authToken = null;
+const licenseServer = 'https://cwip-shaka-proxy.appspot.com/header_auth';
+const authTokenServer = 'https://cwip-shaka-proxy.appspot.com/get_auth_token';
+const authToken = null;
 ```
 
 Now change the request filter:
@@ -215,11 +215,11 @@ Now change the request filter:
 
     console.log('Need auth token.');
     // Start an asynchronous request, and return a Promise chain based on that.
-    var authRequest = {
+    const authRequest = {
       uris: [authTokenServer],
       method: 'POST',
     };
-    var requestType = shaka.net.NetworkingEngine.RequestType.APP;
+    const requestType = shaka.net.NetworkingEngine.RequestType.APP;
     return player.getNetworkingEngine().request(requestType, authRequest)
         .promise.then(function(response) {
           // This endpoint responds with the value we should use in the header.

docs/tutorials/license-wrapping.md

@@ -36,9 +36,9 @@ To start, we're going to use the code from {@tutorial basic-usage}, but use this
 manifest and license server:
 
 ```js
-var manifestUri =
+const manifestUri =
     'https://storage.googleapis.com/shaka-demo-assets/sintel-widevine/dash.mpd';
-var licenseServer = 'https://cwip-shaka-proxy.appspot.com/wrapped_request';
+const licenseServer = 'https://cwip-shaka-proxy.appspot.com/wrapped_request';
 ```
 
 We'll also need to configure the player to use this license server before it
@@ -64,13 +64,13 @@ license request, we must register a request filter:
 ```js
   player.getNetworkingEngine().registerRequestFilter(function(type, request) {
     // Alias some utilities provided by the library.
-    var StringUtils = shaka.util.StringUtils;
-    var Uint8ArrayUtils = shaka.util.Uint8ArrayUtils;
+    const StringUtils = shaka.util.StringUtils;
+    const Uint8ArrayUtils = shaka.util.Uint8ArrayUtils;
 
     // Only manipulate license requests:
     if (type == shaka.net.NetworkingEngine.RequestType.LICENSE) {
       // Create the wrapped request structure.
-      var wrapped = {};
+      const wrapped = {};
 
       // Encode the raw license request in base64.
       // The server we are using in this tutorial expects this field and this
@@ -89,7 +89,7 @@ license request, we must register a request filter:
       wrapped.pEqualsNP = false;  // maybe?
 
       // Encode the wrapped request as JSON.
-      var wrappedJson = JSON.stringify(wrapped);
+      const wrappedJson = JSON.stringify(wrapped);
       // Convert the JSON string back into an ArrayBuffer to replace the request
       // body.
       request.body = StringUtils.toUTF8(wrappedJson);
@@ -123,7 +123,7 @@ that looks like this:
 Change the license server to:
 
 ```js
-var licenseServer =
+const licenseServer =
     'https://cwip-shaka-proxy.appspot.com/wrapped_request_and_response';
 ```
 
@@ -135,18 +135,18 @@ using a request filter:
 ```js
   player.getNetworkingEngine().registerResponseFilter(function(type, response) {
     // Alias some utilities provided by the library.
-    var StringUtils = shaka.util.StringUtils;
-    var Uint8ArrayUtils = shaka.util.Uint8ArrayUtils;
+    const StringUtils = shaka.util.StringUtils;
+    const Uint8ArrayUtils = shaka.util.Uint8ArrayUtils;
 
     // Only manipulate license responses:
     if (type == shaka.net.NetworkingEngine.RequestType.LICENSE) {
       // This is the wrapped license, which is a JSON string.
-      var wrappedString = StringUtils.fromUTF8(response.data);
+      const wrappedString = StringUtils.fromUTF8(response.data);
       // Parse the JSON string into an object.
-      var wrapped = JSON.parse(wrappedString);
+      const wrapped = JSON.parse(wrappedString);
 
       // This is a base64-encoded version of the raw license.
-      var rawLicenseBase64 = wrapped.rawLicenseBase64;
+      const rawLicenseBase64 = wrapped.rawLicenseBase64;
       // Decode that base64 string into a Uint8Array and replace the response
       // data.  The raw license will be fed to the Widevine CDM.
       response.data = Uint8ArrayUtils.fromBase64(rawLicenseBase64);

docs/tutorials/manifest-parser.md

@@ -21,8 +21,8 @@ MyManifestParser.prototype.configure = function(config) {
 };
 
 MyManifestParser.prototype.start = async function(uri, playerInterface) {
-  var type = shaka.net.NetworkingEngine.RequestType.MANIFEST;
-  var request = {
+  const type = shaka.net.NetworkingEngine.RequestType.MANIFEST;
+  const request = {
     uris: [uri],
     method: 'GET',
     retryParameters: this.config_.retryParameters
@@ -181,10 +181,10 @@ It handles merging new segments, and expanding the list of segments for live
 streams.
 
 ```js
-var references = refs.map(function(r) {
+const references = refs.map(function(r) {
   // Should return an array of possible URI choices; this is used for failover
   // in the event of network error.  This is a function to defer calculations.
-  var getUris = function() { return [r.uri]; };
+  const getUris = function() { return [r.uri]; };
 
   return new shaka.media.SegmentReference(
       r.start, r.end, getUris,
@@ -196,7 +196,7 @@ var references = refs.map(function(r) {
       /* appendWindowEnd */ Infinity);
 });
 
-var index = new shaka.media.SegmentIndex(references);
+const index = new shaka.media.SegmentIndex(references);
 ```
 
 To merge updates, simply create a new array of segments and call `merge`.  Any
@@ -242,7 +242,7 @@ MyManifestParser.prototype.loadManifest_ = function(data) {
   // |data| is the response data from load(); but in this example, we ignore it.
 
   // The arguments are only used for live.
-  var timeline = new shaka.media.PresentationTimeline(null, 0);
+  const timeline = new shaka.media.PresentationTimeline(null, 0);
   timeline.setDuration(3600);  // seconds
 
   return {
@@ -276,11 +276,11 @@ MyManifestParser.prototype.loadVariant_ = function(hasVideo, hasAudio) {
 };
 
 MyManifestParser.prototype.loadStream_ = function(type) {
-  var getUris = function() { return ['https://example.com/init']; };
-  var initSegmentReference = new shaka.media.InitSegmentReference(getUris,
+  const getUris = function() { return ['https://example.com/init']; };
+  const initSegmentReference = new shaka.media.InitSegmentReference(getUris,
       /* startByte= */ 0, /* endByte= */ null);
 
-  var index = new shaka.media.SegmentIndex([
+  const index = new shaka.media.SegmentIndex([
     // Times are in seconds, relative to the presentation
     this.loadReference_(0, 0, 10, initSegmentReference),
     this.loadReference_(1, 10, 20, initSegmentReference),
@@ -321,7 +321,7 @@ MyManifestParser.prototype.loadStream_ = function(type) {
 
 MyManifestParser.prototype.loadReference_ =
     function(position, start, end, initSegmentReference) {
-  var getUris = function() { return ['https://example.com/ref_' + position]; };
+  const getUris = function() { return ['https://example.com/ref_' + position]; };
   return new shaka.media.SegmentReference(
       start, end, getUris,
       /* startByte */ 0,