TestMu 2025 - The Largest Virtual Software Testing Conference is Back | 50,000+ Attendees

How to use addTrappedEventListener method in Playwright Internal

Best JavaScript code snippet using playwright-internal

DOMModernPluginEventSystem.js

...139  listenerMap: Map<DOMTopLevelEventType | string, null | (any => void)>,140): void {141  if (!listenerMap.has(topLevelType)) {142    const isCapturePhase = capturePhaseEvents.has(topLevelType);143    addTrappedEventListener(rootContainerElement, topLevelType, isCapturePhase);144    listenerMap.set(topLevelType, null);145  }146}147export function listenToEvent(148  registrationName: string,149  rootContainerElement: Element,150): void {151  const listenerMap = getListenerMapForElement(rootContainerElement);152  const dependencies = registrationNameDependencies[registrationName];153  for (let i = 0; i < dependencies.length; i++) {154    const dependency = dependencies[i];155    listenToTopLevelEvent(dependency, rootContainerElement, listenerMap);156  }157}158const validFBLegacyPrimerRels = new Set([159  'dialog',160  'dialog-post',161  'async',162  'async-post',163  'theater',164  'toggle',165]);166function willDeferLaterForFBLegacyPrimer(nativeEvent: any): boolean {167  let node = nativeEvent.target;168  const type = nativeEvent.type;169  if (type !== 'click') {170    return false;171  }172  while (node !== null) {173    // Primer works by intercepting a click event on an <a> element174    // that has a "rel" attribute that matches one of the valid ones175    // in the Set above. If we intercept this before Primer does, we176    // will need to defer the current event till later and discontinue177    // execution of the current event. To do this we can add a document178    // event listener and continue again later after propagation.179    if (node.tagName === 'A' && validFBLegacyPrimerRels.has(node.rel)) {180      const legacyFBSupport = true;181      const isCapture = nativeEvent.eventPhase === 1;182      addTrappedEventListener(183        document,184        ((type: any): DOMTopLevelEventType),185        isCapture,186        legacyFBSupport,187      );188      return true;189    }190    node = node.parentNode;191  }192  return false;193}194function isMatchingRootContainer(195  grandContainer: Element,196  rootContainer: Document | Element,...

index.js

Source: index.js

...22    }23    listenToNativeEvent(domEventName, container, true);24  })25}26function addTrappedEventListener(27  domEventName,28  container,29  isCapturePhaseListener,30  eventSystemFlags31){32  const listener = createEventListener(33    container,34    domEventName,35    eventSystemFlags36  );37  addListener(container, domEventName, listener, isCapturePhaseListener)38}39export const IS_NON_DELEGATED = 1 << 1;40export const IS_CAPTURE_PHASE = 1 << 2;41export function listenToNonDelegatedEvent(domEventName, target){42  const isCapturePhaseListener = false;43  const listenerSet = getEventListenerSet(target);44  const listenerSetKey = getListenerSetKey(45    domEventName, 46    isCapturePhaseListener47  );48  if(!listenerSet.has(listenerSetKey)){49    addTrappedEventListener(50      domEventName,51      target,52      isCapturePhaseListener,53      IS_NON_DELEGATED54    );55    listenerSet.add(listenerSetKey);56  }57}58function getListenerSetKey(domEventName,capture){59  return `${domEventName}__${capture ? 'capture' : 'bubble'}`;60}61function listenToNativeEvent(domEventName, target, isCapturePhaseListener){62  let eventSystemFlags = 0;63  if (isCapturePhaseListener){64    eventSystemFlags |= IS_CAPTURE_PHASE;65  }66  addTrappedEventListener(67    domEventName,68    target,69    isCapturePhaseListener,70    eventSystemFlags71  )72}73function executeDispatch(curTarget, listener, event){74  const type = event.type || 'unknown-event';75  event.curTarget = curTarget;76  const funcArgs = Array.prototype.slice.call(arguments, 2);77  listener.apply(undefined, funcArgs);78  event.curTarget = null;79}80function processDispatchQueueItemsInOrder(...

DOMPluginEvnentSystem.js

Source: DOMPluginEvnentSystem.js

...36    // å¦ææ²¡æç»å®è¿ï¼å°±æ·»å ä¸è¿ä¸ªkey37    if (isCapturePhaseListener) {38      eventSystemFlags |= IS_CAPTURE_PHASE // let a = 1; a+=239    }40    addTrappedEventListener(41      rootContainerElement,42      domEventName,43      eventSystemFlags,44      isCapturePhaseListener45    )46    listenerSet.add(listenerSetKey)47  }48}49function addTrappedEventListener(50  rootContainerElement,51  domEventName,52  eventSystemFlags,53  isCapturePhaseListener54) {55  let listener = dispatchEvent.bind(56    null,57    domEventName,58    eventSystemFlags,59    rootContainerElement60  )61  if (isCapturePhaseListener) {62    addEventCaptureListener(rootContainerElement, domEventName, listener)63  } else {...

DOMPluginEventSystem.js

Source: DOMPluginEventSystem.js

...126  if (!listenerSet.has(listenerSetKey)) {127    if (isCapturePhaseListener) {128      eventSystemFlags |= IS_CAPTURE_PHASE;129    }130    addTrappedEventListener(131      target,132      domEventName,133      eventSystemFlags,134      isCapturePhaseListener135    );136    listenerSet.add(listenerSetKey);137  }138};139const listenToAllSupportedEvents = (rootContainerElement) => {140  if (rootContainerElement[listeningMarker]) return;141  rootContainerElement[listeningMarker] = true;142  allNativeEvents.forEach((domEventName) => {143    if (!nonDelegatedEvents.has(domEventName)) {144      listenToNativeEvent(domEventName, false, rootContainerElement, null);145    }146    listenToNativeEvent(domEventName, true, rootContainerElement, null);147  });148};149const listenToNonDelegatedEvent = (domEventName, targetElement) => {150  const isCapturePhaseListener = false;151  const listenerSet = getEventListenerSet(targetElement);152  const listenerSetKey = getListenerSetKey(153    domEventName,154    isCapturePhaseListener155  );156  if (!listenerSet.has(listenerSetKey)) {157    addTrappedEventListener(158      targetElement,159      domEventName,160      IS_NON_DELEGATED,161      isCapturePhaseListener162    );163    listenerSet.add(listenerSetKey);164  }165};166export {167  mediaEventTypes,168  nonDelegatedEvents,169  getListenerSetKey,170  listenToNativeEvent,171  listenToAllSupportedEvents,...

Using AI Code Generation

1const playwright = require('playwright');2const { addTrappedEventListener } = require('playwright/lib/internal/frames');3(async () => {4  const browser = await playwright.chromium.launch();5  const page = await browser.newPage();6  await addTrappedEventListener(page, 'request', (event) => {7    console.log('Request intercepted: ', event.url());8  });9  await page.click('input[name="q"]');10  await page.keyboard.type('Playwright');11  await page.keyboard.press('Enter');12  await page.waitForNavigation();13  await browser.close();14})();15import playwright from 'playwright';16import { addTrappedEventListener } from 'playwright/lib/internal/frames';17(async () => {18  const browser = await playwright.chromium.launch();19  const page = await browser.newPage();20  await addTrappedEventListener(page, 'request', (event) => {21    console.log('Request intercepted: ', event.url());22  });23  await page.click('input[name="q"]');24  await page.keyboard.type('Playwright');25  await page.keyboard.press('Enter');26  await page.waitForNavigation();27  await browser.close();28})();

Using AI Code Generation

1const { addTrappedEventListener } = require('playwright/lib/utils/events');2const { addTrappedEventListener } = require('playwright/lib/utils/events');3addTrappedEventListener(document, 'click', (event) => {4  console.log('click', event);5});6addTrappedEventListener(document, 'keydown', (event) => {7  console.log('keydown', event);8});9const { addTrappedEventListener } = require('playwright/lib/utils/events');10addTrappedEventListener(document, 'click', (event) => {11  console.log('click', event);12});13addTrappedEventListener(document, 'keydown', (event) => {14  console.log('keydown', event);15});16const { addTrappedEventListener } = require('playwright/lib/utils/events');17addTrappedEventListener(document, 'click', (event) => {18  console.log('click', event);19});20addTrappedEventListener(document, 'keydown', (event) => {21  console.log('keydown', event);22});23const { addTrappedEventListener } = require('playwright/lib/utils/events');24addTrappedEventListener(document, 'click', (event) => {25  console.log('click', event);26});27addTrappedEventListener(document, 'keydown', (event) => {28  console.log('keydown', event);29});30const { addTrappedEventListener } = require('playwright/lib/utils/events');31addTrappedEventListener(document, 'click', (event) => {32  console.log('click', event);33});34addTrappedEventListener(document, 'keydown', (event) => {35  console.log('keydown', event);36});37const { addTrappedEventListener } = require('playwright/lib/utils/events');38addTrappedEventListener(document, 'click', (event) => {39  console.log('click', event);40});41addTrappedEventListener(document, 'keydown', (event) => {42  console.log('keydown', event);43});44const { addTrappedEventListener } = require('playwright/lib/utils/events');45addTrappedEventListener(document, 'click', (event) => {46  console.log('click', event);47});48addTrappedEventListener(document, 'keydown', (event) => {49  console.log('keydown', event

Using AI Code Generation

1const { addTrappedEventListener } = require('playwright/lib/server/dom');2const { chromium } = require('playwright');3const fs = require('fs');4(async () => {5  const browser = await chromium.launch({6  });7  const page = await browser.newPage();8  const client = await page.context().newCDPSession(page);9  await client.send('Runtime.enable');10  await addTrappedEventListener(client, {11    handler: (event) => {12      console.log('event: ', event);13      fs.appendFileSync('output.txt', event.args[0].value + "14");15    },16    predicate: (event) => event.type === 'log',17  });

Using AI Code Generation

1const { addTrappedEventListener } = require('playwright/lib/client/frames');2const { firefox } = require('playwright');3(async () => {4  const browser = await firefox.launch({5  });6  const context = await browser.newContext();7  const page = await context.newPage();8  await addTrappedEventListener(page, 'load', async (event) => {9    console.log('load event is fired');10  });11  await page.click('text=English');12  await page.waitForLoadState('load');13  await browser.close();14})();

Using AI Code Generation

1const {addTrappedEventListener} = require('playwright/lib/utils/events');2const {Page} = require('playwright/lib/server/page');3const {Frame} = require('playwright/lib/server/frame');4const page = new Page();5const frame = new Frame();6const clickHandler = (event) => {7  console.log('Click event captured');8};9addTrappedEventListener(frame, 'click', clickHandler);10frame.emit('click');11const {addTrappedEventListener} = require('playwright/lib/utils/events');12const {Page} = require('playwright/lib/server/page');13const {Frame} = require('playwright/lib/server/frame');14const page = new Page();15const frame = new Frame();16const clickHandler = (event) => {17  console.log('Click event captured');18};19addTrappedEventListener(frame, 'click', clickHandler);20frame.emit('click');

Using AI Code Generation

1In order to use the above methods, you need to import the internal API as below:2const { addTrappedEventListener, removeTrappedEventListener, removeAllTrappedEventListeners } = require('@playwright/test/lib/server/trace/viewer/internal');3addTrappedEventListener(page, 'request', (request) => {4    console.log(request.url());5  });6  removeTrappedEventListener(page, 'request', (request) => {7    console.log(request.url());8  });9  removeAllTrappedEventListeners(page);10import { test, expect } from '@playwright/test';11import { addTrappedEventListener, removeTrappedEventListener, removeAllTrappedEventListeners } from '@playwright/test/lib/server/trace/viewer/internal';12test('test', async ({ page }) => {13  addTrappedEventListener(page, 'request', (request) => {14    console.log(request.url());15  });16  removeTrappedEventListener(page, 'request', (request) => {17    console.log(request.url());18  });19  removeAllTrappedEventListeners(page);20});

Using AI Code Generation

1const { addTrappedEventListener } = require('playwright/lib/server/dom.js');2addTrappedEventListener(window, 'click', (e) => {3  e.preventDefault();4  console.log('Click event is trapped');5});6const { addTrappedEventListener } = require('puppeteer/lib/ExecutionContext.js');7addTrappedEventListener(window, 'click', (e) => {8  e.preventDefault();9  console.log('Click event is trapped');10});11const { addTrappedEventListener } = require('cypress/lib/server/dom.js');12addTrappedEventListener(window, 'click', (e) => {13  e.preventDefault();14  console.log('Click event is trapped');15});16const { addTrappedEventListener } = require('testcafe-hammerhead/lib/client/sandbox/event/listeners.js');17addTrappedEventListener(window, 'click', (e) => {18  e.preventDefault();19  console.log('Click event is trapped');20});

Using AI Code Generation

1await addTrappedEventListener(window, 'all', (event) => {2  console.log(event);3});4await addTrappedEventListener(window, 'all', (event) => {5  console.log(event);6});7await addTrappedEventListener(window, 'all', (event) => {8  console.log(event);9});10await addTrappedEventListener(window, 'all', (event) => {11  console.log(event);12});13await addTrappedEventListener(window, 'all', (event) => {14  console.log(event);15});16await addTrappedEventListener(window, 'all', (event) => {17  console.log(event);18});19await addTrappedEventListener(window, 'all', (event) => {20  console.log(event);21});

StackOverFlow community discussions

Questions

Discussion

Jest + Playwright - Test callbacks of event-based DOM library

Is it possible to get the selector from a locator object in playwright?

How to run a list of test suites in a single file concurrently in jest?

firefox browser does not start in playwright

Running Playwright in Azure Function

This question is quite close to a "need more focus" question. But let's try to give it some focus:

Does Playwright has access to the cPicker object on the page? Does it has access to the window object?

Yes, you can access both cPicker and the window object inside an evaluate call.

Should I trigger the events from the HTML file itself, and in the callbacks, print in the DOM the result, in some dummy-element, and then infer from that dummy element text that the callbacks fired?

Exactly, or you can assign values to a javascript variable:

const cPicker = new ColorPicker({
  onClickOutside(e){
  },
  onInput(color){
    window['color'] = color;
  },
  onChange(color){
    window['result'] = color;
  }
})

And then

it('Should call all callbacks with correct arguments', async() => {
    await page.goto(`http://localhost:5000/tests/visual/basic.html`, {waitUntil:'load'})

    // Wait until the next frame
    await page.evaluate(() => new Promise(requestAnimationFrame))

    // Act
   
    // Assert
    const result = await page.evaluate(() => window['color']);
    // Check the value
})

https://stackoverflow.com/questions/65477895/jest-playwright-test-callbacks-of-event-based-dom-library

Well this is one way, but not sure if it will work for all possible locators!.

// Get a selector from a playwright locator
import { Locator } from "@playwright/test";
export function extractSelector(locator: Locator) {
    const selector = locator.toString();
    const parts = selector.split("@");
    if (parts.length !== 2) { throw Error("extractSelector: susupect that this is not a locator"); }
    if (parts[0] !== "Locator") { throw Error("extractSelector: did not find locator"); }
    return parts[1];
}

https://stackoverflow.com/questions/72044959/is-it-possible-to-get-the-selector-from-a-locator-object-in-playwright

Assuming you are not running test with the --runinband flag, the simple answer is yes but it depends ????

There is a pretty comprehensive GitHub issue jest#6957 that explains certain cases of when tests are run concurrently or in parallel. But it seems to depend on a lot of edge cases where jest tries its best to determine the fastest way to run the tests given the circumstances.

To my knowledge there is no way to force jest to run in parallel.

Aside

Have you considered using playwright instead of puppeteer with jest? Playwright has their own internally built testing library called @playwright/test that is used in place of jest with a similar API. This library allows for explicitly defining test groups in a single file to run in parallel (i.e. test.describe.parallel) or serially (i.e. test.describe.serial). Or even to run all tests in parallel via a config option.

// parallel
test.describe.parallel('group', () => {
  test('runs in parallel 1', async ({ page }) => {});
  test('runs in parallel 2', async ({ page }) => {});
});

// serial
test.describe.serial('group', () => {
  test('runs first', async ({ page }) => {});
  test('runs second', async ({ page }) => {});
});

https://stackoverflow.com/questions/73497773/how-to-run-a-list-of-test-suites-in-a-single-file-concurrently-in-jest

I found the error. It was because of some missing libraries need. I discovered this when I downgraded playwright to version 1.9 and ran the the code then this was the error msg:

(node:12876) UnhandledPromiseRejectionWarning: browserType.launch: Host system is missing dependencies!

Some of the Universal C Runtime files cannot be found on the system. You can fix
that by installing Microsoft Visual C++ Redistributable for Visual Studio from:
https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads

Full list of missing libraries:
    vcruntime140.dll
    msvcp140.dll
Error
    at Object.captureStackTrace (D:\Projects\snkrs-play\node_modules\playwright\lib\utils\stackTrace.js:48:19)
    at Connection.sendMessageToServer (D:\Projects\snkrs-play\node_modules\playwright\lib\client\connection.js:69:48)
    at Proxy.<anonymous> (D:\Projects\snkrs-play\node_modules\playwright\lib\client\channelOwner.js:64:61)
    at D:\Projects\snkrs-play\node_modules\playwright\lib\client\browserType.js:64:67
    at BrowserType._wrapApiCall (D:\Projects\snkrs-play\node_modules\playwright\lib\client\channelOwner.js:77:34)
    at BrowserType.launch (D:\Projects\snkrs-play\node_modules\playwright\lib\client\browserType.js:55:21)
    at D:\Projects\snkrs-play\index.js:4:35
    at Object.<anonymous> (D:\Projects\snkrs-play\index.js:7:3)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:12876) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:12876) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

A list of missing libraries was provided. After successful installments, firefox ran fine. I upgraded again to version 1.10 and firefox still works.

https://stackoverflow.com/questions/66984974/firefox-browser-does-not-start-in-playwright

I found the error. It was because of some missing libraries need. I discovered this when I downgraded playwright to version 1.9 and ran the the code then this was the error msg:

(node:12876) UnhandledPromiseRejectionWarning: browserType.launch: Host system is missing dependencies!

Some of the Universal C Runtime files cannot be found on the system. You can fix
that by installing Microsoft Visual C++ Redistributable for Visual Studio from:
https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads

Full list of missing libraries:
    vcruntime140.dll
    msvcp140.dll
Error
    at Object.captureStackTrace (D:\Projects\snkrs-play\node_modules\playwright\lib\utils\stackTrace.js:48:19)
    at Connection.sendMessageToServer (D:\Projects\snkrs-play\node_modules\playwright\lib\client\connection.js:69:48)
    at Proxy.<anonymous> (D:\Projects\snkrs-play\node_modules\playwright\lib\client\channelOwner.js:64:61)
    at D:\Projects\snkrs-play\node_modules\playwright\lib\client\browserType.js:64:67
    at BrowserType._wrapApiCall (D:\Projects\snkrs-play\node_modules\playwright\lib\client\channelOwner.js:77:34)
    at BrowserType.launch (D:\Projects\snkrs-play\node_modules\playwright\lib\client\browserType.js:55:21)
    at D:\Projects\snkrs-play\index.js:4:35
    at Object.<anonymous> (D:\Projects\snkrs-play\index.js:7:3)
    at Module._compile (internal/modules/cjs/loader.js:1063:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1092:10)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:12876) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:12876) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

A list of missing libraries was provided. After successful installments, firefox ran fine. I upgraded again to version 1.10 and firefox still works.

https://stackoverflow.com/questions/66984974/firefox-browser-does-not-start-in-playwright

Blogs

Check out the latest blogs from LambdaTest on this topic:

How to Recognize and Hire Top QA / DevOps Engineers

With the rising demand for new services and technologies in the IT, manufacturing, healthcare, and financial sector, QA/ DevOps engineering has become the most important part of software companies. Below is a list of some characteristics to look for when interviewing a potential candidate.

How To Use Playwright For Web Scraping with Python

In today’s data-driven world, the ability to access and analyze large amounts of data can give researchers, businesses & organizations a competitive edge. One of the most important & free sources of this data is the Internet, which can be accessed and mined through web scraping.

Two-phase Model-based Testing

Most test automation tools just do test execution automation. Without test design involved in the whole test automation process, the test cases remain ad hoc and detect only simple bugs. This solution is just automation without real testing. In addition, test execution automation is very inefficient.

Failures may be inevitable, but that doesn’t prevent success

April 2020 Platform Updates: New Browser, Better Performance & Much Much More!

Howdy testers! If you’re reading this article I suggest you keep a diary & a pen handy because we’ve added numerous exciting features to our cross browser testing cloud and I am about to share them with you right away!

Playwright tutorial

LambdaTest’s Playwright tutorial will give you a broader idea about the Playwright automation framework, its unique features, and use cases with examples to exceed your understanding of Playwright testing. This tutorial will give A to Z guidance, from installing the Playwright framework to some best practices and advanced concepts.

Chapters:

What is Playwright : Playwright is comparatively new but has gained good popularity. Get to know some history of the Playwright with some interesting facts connected with it.
How To Install Playwright : Learn in detail about what basic configuration and dependencies are required for installing Playwright and run a test. Get a step-by-step direction for installing the Playwright automation framework.
Playwright Futuristic Features: Launched in 2020, Playwright gained huge popularity quickly because of some obliging features such as Playwright Test Generator and Inspector, Playwright Reporter, Playwright auto-waiting mechanism and etc. Read up on those features to master Playwright testing.
What is Component Testing: Component testing in Playwright is a unique feature that allows a tester to test a single component of a web application without integrating them with other elements. Learn how to perform Component testing on the Playwright automation framework.
Inputs And Buttons In Playwright: Every website has Input boxes and buttons; learn about testing inputs and buttons with different scenarios and examples.
Functions and Selectors in Playwright: Learn how to launch the Chromium browser with Playwright. Also, gain a better understanding of some important functions like “BrowserContext,” which allows you to run multiple browser sessions, and “newPage” which interacts with a page.
Handling Alerts and Dropdowns in Playwright : Playwright interact with different types of alerts and pop-ups, such as simple, confirmation, and prompt, and different types of dropdowns, such as single selector and multi-selector get your hands-on with handling alerts and dropdown in Playright testing.
Playwright vs Puppeteer: Get to know about the difference between two testing frameworks and how they are different than one another, which browsers they support, and what features they provide.
Run Playwright Tests on LambdaTest: Playwright testing with LambdaTest leverages test performance to the utmost. You can run multiple Playwright tests in Parallel with the LammbdaTest test cloud. Get a step-by-step guide to run your Playwright test on the LambdaTest platform.
Playwright Python Tutorial: Playwright automation framework support all major languages such as Python, JavaScript, TypeScript, .NET and etc. However, there are various advantages to Python end-to-end testing with Playwright because of its versatile utility. Get the hang of Playwright python testing with this chapter.
Playwright End To End Testing Tutorial: Get your hands on with Playwright end-to-end testing and learn to use some exciting features such as TraceViewer, Debugging, Networking, Component testing, Visual testing, and many more.
Playwright Video Tutorial: Watch the video tutorials on Playwright testing from experts and get a consecutive in-depth explanation of Playwright automation testing.