How to use prerenderChannel method in wpt

Best JavaScript code snippet using wpt

utils.js

Source:utils.js

1const STORE_URL = '/speculation-rules/prerender/resources/key-value-store.py';2function assertSpeculationRulesIsSupported() {3  assert_implements(4      'supports' in HTMLScriptElement,5      'HTMLScriptElement.supports is not supported');6  assert_implements(7      HTMLScriptElement.supports('speculationrules'),8      '<script type="speculationrules"> is not supported');9}10// Starts prerendering for `url`.11function startPrerendering(url) {12  // Adds <script type="speculationrules"> and specifies a prerender candidate13  // for the given URL.14  // TODO(https://crbug.com/1174978): <script type="speculationrules"> may not15  // start prerendering for some reason (e.g., resource limit). Implement a16  // WebDriver API to force prerendering.17  const script = document.createElement('script');18  script.type = 'speculationrules';19  script.text = `{"prerender": [{"source": "list", "urls": ["${url}"] }] }`;20  document.head.appendChild(script);21}22// Reads the value specified by `key` from the key-value store on the server.23async function readValueFromServer(key) {24  const serverUrl = `${STORE_URL}?key=${key}`;25  const response = await fetch(serverUrl);26  if (!response.ok)27    throw new Error('An error happened in the server');28  const value = await response.text();29  // The value is not stored in the server.30  if (value === "")31    return { status: false };32  return { status: true, value: value };33}34// Convenience wrapper around the above getter that will wait until a value is35// available on the server.36async function nextValueFromServer(key) {37  while (true) {38    // Fetches the test result from the server.39    const { status, value } = await readValueFromServer(key);40    if (!status) {41      // The test result has not been stored yet. Retry after a while.42      await new Promise(resolve => setTimeout(resolve, 100));43      continue;44    }45    return value;46  }47}48// Writes `value` for `key` in the key-value store on the server.49async function writeValueToServer(key, value) {50  const serverUrl = `${STORE_URL}?key=${key}&value=${value}`;51  await fetch(serverUrl);52}53// Loads the initiator page, and navigates to the prerendered page after it54// receives the 'readyToActivate' message.55function loadInitiatorPage() {56  // Used to communicate with the prerendering page.57  const prerenderChannel = new BroadcastChannel('prerender-channel');58  window.addEventListener('unload', () => {59    prerenderChannel.close();60  });61  // We need to wait for the 'readyToActivate' message before navigation62  // since the prerendering implementation in Chromium can only activate if the63  // response for the prerendering navigation has already been received and the64  // prerendering document was created.65  const readyToActivate = new Promise((resolve, reject) => {66    prerenderChannel.addEventListener('message', e => {67      if (e.data != 'readyToActivate')68        reject(`The initiator page receives an unsupported message: ${e.data}`);69      resolve(e.data);70    });71  });72  const url = new URL(document.URL);73  url.searchParams.append('prerendering', '');74  // Prerender a page that notifies the initiator page of the page's ready to be75  // activated via the 'readyToActivate'.76  startPrerendering(url.toString());77  // Navigate to the prerendered page after being informed.78  readyToActivate.then(() => {79    window.location = url.toString();80  }).catch(e => {81    const testChannel = new BroadcastChannel('test-channel');82    testChannel.postMessage(83        `Failed to navigate the prerendered page: ${e.toString()}`);84    testChannel.close();85    window.close();86  });87}88// Returns messages received from the given BroadcastChannel89// so that callers do not need to add their own event listeners.90// nextMessage() returns a promise which resolves with the next message.91//92// Usage:93//   const channel = new BroadcastChannel('channel-name');94//   const messageQueue = new BroadcastMessageQueue(channel);95//   const message1 = await messageQueue.nextMessage();96//   const message2 = await messageQueue.nextMessage();97//   message1 and message2 are the messages received.98class BroadcastMessageQueue {99  constructor(broadcastChannel) {100    this.messages = [];101    this.resolveFunctions = [];102    this.channel = broadcastChannel;103    this.channel.addEventListener('message', e => {104      if (this.resolveFunctions.length > 0) {105        const fn = this.resolveFunctions.shift();106        fn(e.data);107      } else {108        this.messages.push(e.data);109      }110    });111  }112  // Returns a promise that resolves with the next message from this queue.113  nextMessage() {114    return new Promise(resolve => {115      if (this.messages.length > 0)116        resolve(this.messages.shift())117      else118        this.resolveFunctions.push(resolve);119    });120  }121}122// Returns <iframe> element upon load.123function createFrame(url) {124  return new Promise(resolve => {125      const frame = document.createElement('iframe');126      frame.src = url;127      frame.onload = () => resolve(frame);128      document.body.appendChild(frame);129    });130}131class PrerenderChannel extends EventTarget {132  broadcastChannel = null;133  constructor(uid, name) {134    super();135    this.broadcastChannel = new BroadcastChannel(`${uid}-${name}`);136    this.broadcastChannel.addEventListener('message', e => {137      this.dispatchEvent(new CustomEvent('message', {detail: e.data}));138    });139  }140  postMessage(message) {141    this.broadcastChannel.postMessage(message);142  }143  close() {144    this.broadcastChannel.close();145  }146};147async function create_prerendered_page(t) {148  const uuid = token();149  new PrerenderChannel(uuid, 'log').addEventListener('message', message => {150    // Calling it with ['log'] to avoid lint issue. This log should be used for debugging151    // the prerendered context, not testing.152    if(window.console)153      console['log']('[From Prerendered]', ...message.detail);154  });155  const execChannel = new PrerenderChannel(uuid, 'exec');156  const initChannel = new PrerenderChannel(uuid, 'initiator');157  const exec = (func, args = []) => {158      const receiver = token();159      execChannel.postMessage({receiver, fn: func.toString(), args});160      return new Promise((resolve, reject) => {161        const channel = new PrerenderChannel(uuid, receiver);162        channel.addEventListener('message', ({detail}) => {163          channel.close();164          if (detail.error)165            reject(detail.error)166          else167            resolve(detail.result);168        });169      })170    };171  window.open(`/speculation-rules/prerender/resources/eval-init.html?uuid=${uuid}`, '_blank', 'noopener');172  t.add_cleanup(() => initChannel.postMessage('close'));173  t.add_cleanup(() => exec(() => window.close()));174  await new Promise(resolve => {175    const channel = new PrerenderChannel(uuid, 'ready');176    channel.addEventListener('message', () => {177      channel.close();178      resolve();179    });180  });181  async function activate() {182    const prerendering = exec(() => new Promise(resolve =>183      document.addEventListener('prerenderingchange', () => {184        resolve(document.prerendering);185      })));186    initChannel.postMessage('activate');187    if (await prerendering)188      throw new Error('Should not be prerendering at this point')189  }190  return {191    exec,192    activate193  };194}195function test_prerender_restricted(fn, expected, label) {196  promise_test(async t => {197    const {exec} = await create_prerendered_page(t);198    let result = null;199    try {200      await exec(fn);201      result = "OK";202    } catch (e) {203      result = e.name;204    }205    assert_equals(result, expected);206  }, label);207}208function test_prerender_defer(fn, label) {209  promise_test(async t => {210    const {exec, activate} = await create_prerendered_page(t);211    let activated = false;212    const deferred = exec(fn);213    const post = new Promise(resolve =>214      deferred.then(result => {215        assert_true(activated, "Deferred operation should occur only after activation");216        resolve(result);217      }));218    await new Promise(resolve => t.step_timeout(resolve, 100));219    await activate();220    activated = true;221    await post;222  }, label);...

deferred-promise-utils.js

Source:deferred-promise-utils.js

1/**2 * This file co-works with a html file and utils.js to test a promise that3 * should be deferred during prerendering.4 *5 * Usage example:6 *  Suppose the html is "prerender-promise-test.html"7 *  On prerendering page, prerender-promise-test.html?prerendering:8 *    const prerenderEventCollector = new PrerenderEventCollector();9 *    const promise = {a promise that should be deferred during prerendering};10 *    prerenderEventCollector.start(promise, {promise name});11 *12 *  On the initiator page, prerender-promise-test.html:13 *   execute14 *    `loadInitiatorPage();`15 */16// Collects events that happen relevant to a prerendering page.17// An event is added when:18// 1. start() is called.19// 2. a prerenderingchange event is dispatched on this document.20// 3. the promise passed to start() is resolved.21// 4. addEvent() is called manually.22class PrerenderEventCollector {23  constructor() {24    this.eventsSeen_ = [];25  }26  // Adds an event to `eventsSeen_` along with the prerendering state of the27  // page.28  addEvent(eventMessage) {29    this.eventsSeen_.push(30        {event: eventMessage, prerendering: document.prerendering});31  }32  // Starts collecting events until the promise resolves. Triggers activation by33  // telling the initiator page that it is ready for activation.34  async start(promise, promiseName) {35    assert_true(document.prerendering);36    this.addEvent(`started waiting ${promiseName}`);37    promise38        .then(39            () => {40              this.addEvent(`finished waiting ${promiseName}`);41            },42            (error) => {43              if (error instanceof Error)44                error = error.name;45              this.addEvent(`${promiseName} rejected: ${error}`);46            })47        .finally(() => {48          // Used to communicate with the main test page.49          const testChannel = new BroadcastChannel('test-channel');50          // Send the observed events back to the main test page.51          testChannel.postMessage(this.eventsSeen_);52          testChannel.close();53          window.close();54        });55    document.addEventListener('prerenderingchange', () => {56      this.addEvent('prerendering change');57    });58    // Post a task to give the implementation a chance to fail in case it59    // resolves a promise without waiting for activation.60    setTimeout(() => {61      // Used to communicate with the initiator page.62      const prerenderChannel = new BroadcastChannel('prerender-channel');63      // Inform the initiator page that this page is ready to be activated.64      prerenderChannel.postMessage('readyToActivate');65      prerenderChannel.close();66    }, 0);67  }...

Using AI Code Generation

1var wpt = require('webpagetest');2var api = new wpt('www.webpagetest.org');3var options = {4};5api.prerenderChannel(options, function(err, data) {6  if (err) {7    console.log(err);8  } else {9    console.log(data);10  }11});12{ statusCode: 200,13   { statusCode: 200,14      { statusCode: 200,

Using AI Code Generation

1var wpt = require('webpagetest');2var wpt = new WebPageTest('www.webpagetest.org');3  if (err) console.error(err);4  else console.log(data);5});6var wpt = require('webpagetest');7var wpt = new WebPageTest('www.webpagetest.org');8  if (err) console.error(err);9  else console.log(data);10});11var wpt = require('webpagetest');12var wpt = new WebPageTest('www.webpagetest.org');13wpt.getLocations(function(err, data) {14  if (err) console.error(err);15  else console.log(data);16});17var wpt = require('webpagetest');18var wpt = new WebPageTest('www.webpagetest.org');19wpt.getTesters(function(err, data) {20  if (err) console.error(err);21  else console.log(data);22});23var wpt = require('webpagetest');24var wpt = new WebPageTest('www.webpagetest.org');25wpt.getBrowsers(function(err, data) {26  if (err) console.error(err);27  else console.log(data);28});29var wpt = require('webpagetest');30var wpt = new WebPageTest('www.webpagetest.org');31wpt.getTesters(function(err, data) {32  if (err) console.error(err);33  else console.log(data);34});35var wpt = require('webpagetest');36var wpt = new WebPageTest('www.webpagetest.org');37wpt.getTesters(function(err, data) {38  if (err) console.error(err);39  else console.log(data);40});

Using AI Code Generation

1var wpt = require('webpagetest');2var options = { host: 'www.webpagetest.org', key: 'A.12345678901234567890123456789012', timeout: 10000 };3var wpt = new WebPageTest('www.webpagetest.org', 'A.12345678901234567890123456789012');4wpt.prerenderChannel(url, function(err, data) {5  if (err) {6    console.log(err);7  } else {8    console.log(data);9  }10});

Using AI Code Generation

1var wptdriver = require('wptdriver');2var driver = new wptdriver.WptDriver();3  if (err) {4    console.log('Error: ', err);5  } else {6    console.log('Result: ', res);7  }8});

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