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

How to use extractLangs method in Playwright Internal

Best JavaScript code snippet using playwright-internal

api_parser.js

...67        extendsName = member.text.substring('extends: ['.length, member.text.indexOf(']'));68        continue;69      }70    }71    const clazz = new Documentation.Class(extractLangs(node), name, [], extendsName, extractComments(node));72    this.classes.set(clazz.name, clazz);73  }74  /**75   * @param {MarkdownNode} spec76   */77  parseMember(spec) {78    const match = spec.text.match(/(event|method|property|async method): ([^.]+)\.(.*)/);79    if (!match)80      throw new Error('Invalid member: ' + spec.text);81    const name = match[3];82    let returnType = null;83    for (const item of spec.children || []) {84      if (item.type === 'li' && item.liType === 'default')85        returnType = this.parseType(item);86    }87    if (!returnType)88      returnType = new Documentation.Type('void');89    let member;90    if (match[1] === 'event')91      member = Documentation.Member.createEvent(extractLangs(spec), name, returnType, extractComments(spec));92    if (match[1] === 'property')93      member = Documentation.Member.createProperty(extractLangs(spec), name, returnType, extractComments(spec));94    if (match[1] === 'method' || match[1] === 'async method') {95      member = Documentation.Member.createMethod(extractLangs(spec), name, [], returnType, extractComments(spec));96      if (match[1] === 'async method')97        member.async = true;98    }99    const clazz = this.classes.get(match[2]);100    const existingMember = clazz.membersArray.find(m => m.name === name && m.kind === member.kind);101    if (existingMember && isTypeOverride(existingMember, member)) {102      for (const lang of member.langs.only) {103        existingMember.langs.types = existingMember.langs.types || {};104        existingMember.langs.types[lang] = returnType;105      }106    } else {107      clazz.membersArray.push(member);108    }109  }110  /**111   * @param {MarkdownNode} spec112   */113  parseArgument(spec) {114    const match = spec.text.match(/(param|option): (.*)/);115    if (!match)116      throw `Something went wrong with matching ${spec.text}`;117    // For "test.describe.only.title":118    // - className is "test"119    // - methodName is "describe.only"120    // - argument name is "title"121    const parts = match[2].split('.');122    const className = parts[0];123    const name = parts[parts.length - 1];124    const methodName = parts.slice(1, parts.length - 1).join('.');125    const clazz = this.classes.get(className);126    if (!clazz)127      throw new Error('Invalid class ' + className);128    const method = clazz.membersArray.find(m => m.kind === 'method' && m.name === methodName);129    if (!method)130      throw new Error(`Invalid method ${className}.${methodName} when parsing: ${match[0]}`);131    if (!name)132      throw new Error('Invalid member name ' + spec.text);133    if (match[1] === 'param') {134      const arg = this.parseProperty(spec);135      arg.name = name;136      const existingArg = method.argsArray.find(m => m.name === arg.name);137      if (existingArg && isTypeOverride(existingArg, arg)) {138        if (!arg.langs || !arg.langs.only)139          throw new Error('Override does not have lang: ' + spec.text);140        for (const lang of arg.langs.only) {141          existingArg.langs.overrides = existingArg.langs.overrides || {};142          existingArg.langs.overrides[lang] = arg;143        }144      } else {145        method.argsArray.push(arg);146      }147    } else {148      let options = method.argsArray.find(o => o.name === 'options');149      if (!options) {150        const type = new Documentation.Type('Object', []);151        options = Documentation.Member.createProperty({}, 'options', type, undefined, false);152        method.argsArray.push(options);153      }154      const p = this.parseProperty(spec);155      p.required = false;156      options.type.properties.push(p);157    }158  }159  /**160   * @param {MarkdownNode} spec161   */162  parseProperty(spec) {163    const param = childrenWithoutProperties(spec)[0];164    const text = param.text;165    const name = text.substring(0, text.indexOf('<')).replace(/\`/g, '').trim();166    const comments = extractComments(spec);167    return Documentation.Member.createProperty(extractLangs(spec), name, this.parseType(param), comments, guessRequired(md.render(comments)));168  }169  /**170   * @param {MarkdownNode=} spec171   * @return {Documentation.Type}172   */173  parseType(spec) {174    const arg = parseVariable(spec.text);175    const properties = [];176    for (const child of spec.children || []) {177      const { name, text } = parseVariable(child.text);178      const comments = /** @type {MarkdownNode[]} */ ([{ type: 'text', text }]);179      properties.push(Documentation.Member.createProperty({}, name, this.parseType(child), comments, guessRequired(text)));180    }181    return Documentation.Type.parse(arg.type, properties);182  }183}184/**185 * @param {string} line186 * @returns {{ name: string, type: string, text: string }}187 */188function parseVariable(line) {189  let match = line.match(/^`([^`]+)` (.*)/);190  if (!match)191    match = line.match(/^(returns): (.*)/);192  if (!match)193    match = line.match(/^(type): (.*)/);194  if (!match)195    match = line.match(/^(argument): (.*)/);196  if (!match)197    throw new Error('Invalid argument: ' + line);198  const name = match[1];199  const remainder = match[2];200  if (!remainder.startsWith('<'))201    throw new Error(`Bad argument: "${name}" in "${line}"`);202  let depth = 0;203  for (let i = 0; i < remainder.length; ++i) {204    const c = remainder.charAt(i);205    if (c === '<')206      ++depth;207    if (c === '>')208      --depth;209    if (depth === 0)210      return { name, type: remainder.substring(1, i), text: remainder.substring(i + 2) };211  }212  throw new Error('Should not be reached');213}214/**215 * @param {MarkdownNode[]} body216 * @param {MarkdownNode[]} params217 */218function applyTemplates(body, params) {219  const paramsMap = new Map();220  for (const node of params)221    paramsMap.set('%%-' + node.text + '-%%', node);222  const visit = (node, parent) => {223    if (node.text && node.text.includes('-inline- = %%')) {224      const [name, key] = node.text.split('-inline- = ');225      const list = paramsMap.get(key);226      const newChildren = [];227      if (!list)228        throw new Error('Bad template: ' + key);229      for (const prop of list.children) {230        const template = paramsMap.get(prop.text);231        if (!template)232          throw new Error('Bad template: ' + prop.text);233        const children = childrenWithoutProperties(template);234        const { name: argName } = parseVariable(children[0].text);235        newChildren.push({236          type: node.type,237          text: name + argName,238          children: template.children.map(c => md.clone(c))239        });240      }241      const nodeIndex = parent.children.indexOf(node);242      parent.children = [...parent.children.slice(0, nodeIndex), ...newChildren, ...parent.children.slice(nodeIndex + 1)];243    } else if (node.text && node.text.includes(' = %%')) {244      const [name, key] = node.text.split(' = ');245      node.text = name;246      const template = paramsMap.get(key);247      if (!template)248        throw new Error('Bad template: ' + key);249      node.children.push(...template.children.map(c => md.clone(c)));250    }251    for (const child of node.children || [])252      visit(child, node);253    if (node.children)254      node.children = node.children.filter(child => !child.text || !child.text.includes('-inline- = %%'));255  };256  for (const node of body)257    visit(node, null);258  return body;259}260/**261 * @param {MarkdownNode} item262 * @returns {MarkdownNode[]}263 */264function extractComments(item) {265  return (item.children || []).filter(c => {266    if (c.type.startsWith('h'))267      return false;268    if (c.type === 'li' && c.liType === 'default')269      return false;270    if (c.type === 'li' && c.text.startsWith('langs:'))271      return false;272    return true;273  });274}275/**276 * @param {string} comment277 */278function guessRequired(comment) {279  let required = true;280  if (comment.toLowerCase().includes('defaults to '))281    required = false;282  if (comment.startsWith('Optional'))283    required = false;284  if (comment.endsWith('Optional.'))285    required = false;286  if (comment.toLowerCase().includes('if set'))287    required = false;288  if (comment.toLowerCase().includes('if applicable'))289    required = false;290  if (comment.toLowerCase().includes('if available'))291    required = false;292  return required;293}294/**295 * @param {string} apiDir296 * @param {string=} paramsPath297 */298function parseApi(apiDir, paramsPath) {299  return new ApiParser(apiDir, paramsPath).documentation;300}301/**302 * @param {MarkdownNode} spec303 * @returns {import('./documentation').Langs}304 */305function extractLangs(spec) {306  for (const child of spec.children) {307    if (child.type !== 'li' || child.liType !== 'bullet' || !child.text.startsWith('langs:'))308      continue;309    const only = child.text.substring('langs:'.length).trim();310    /** @type {Object<string, string>} */311    const aliases = {};312    for (const p of child.children || []) {313      const match = p.text.match(/alias-(\w+)[\s]*:(.*)/);314      if (match)315        aliases[match[1].trim()] = match[2].trim();316    }317    return {318      only: only ? only.split(',').map(l => l.trim()) : undefined,319      aliases,...

i18n.js

Source: i18n.js

...14  var locales2paths = {};15  // Puts the paths of all locale files contained in a given directory16  // into `locales2paths` (files from various dirs are grouped by lang code)17  // (only json files with valid language code as name)18  function extractLangs(dir) {19    if(!existsSync(dir)) return;20    var stat = fs.lstatSync(dir);21    if (!stat.isDirectory() || stat.isSymbolicLink()) return;22    fs.readdirSync(dir).forEach(function(file) {23      file = path.resolve(dir, file);24      stat = fs.lstatSync(file);25      if (stat.isDirectory() || stat.isSymbolicLink()) return;26      var ext = path.extname(file)27      , locale = path.basename(file, ext).toLowerCase();28      if ((ext == '.json') && languages.isValid(locale)) {29        if(!locales2paths[locale]) locales2paths[locale] = [];30        locales2paths[locale].push(file);31      }32    });33  }34  //add core supported languages first35  extractLangs(npm.root+"/ep_etherpad-lite/locales");36  37  //add plugins languages (if any)38  for(var pluginName in plugins) extractLangs(path.join(npm.root, pluginName, 'locales'));39  // Build a locale index (merge all locale data)40  var locales = {}41  _.each (locales2paths, function(files, langcode) {42    locales[langcode]={};43    files.forEach(function(file) {44     var fileContents = JSON.parse(fs.readFileSync(file,'utf8'));45      _.extend(locales[langcode], fileContents);46    });47  });48  return locales;49}50// returns a hash of all available languages availables with nativeName and direction51// e.g. { es: {nativeName: "espaÃ±ol", direction: "ltr"}, ... }52function getAvailableLangs(locales) {...

Using AI Code Generation

1const { extractLangs } = require('playwright-core/lib/server/i18n');2console.log(extractLangs('en,fr,de'));3console.log(extractLangs('en,fr,de', 'en'));4const { extractLangs } = require('playwright-core/lib/server/i18n');5console.log(extractLangs('en,fr,de'));6console.log(extractLangs('en,fr,de', 'en'));7const { extractLangs } = require('playwright-core/lib/server/i18n');8console.log(extractLangs('en,fr,de'));9console.log(extractLangs('en,fr,de', 'en'));10const { extractLangs } = require('playwright-core/lib/server/i18n');11console.log(extractLangs('en,fr,de'));12console.log(extractLangs('en,fr,de', 'en'));13const { extractLangs } = require('playwright-core/lib/server/i18n');14console.log(extractLangs('en,fr,de'));15console.log(extractLangs('en,fr,de', 'en'));16const { extractLangs } = require('playwright-core/lib/server/i18n');17console.log(extractLangs('en,fr,de'));18console.log(extractLangs('en,fr,de', 'en'));

Using AI Code Generation

1const { extractLangs } = require('playwright/lib/server/common/supplements.js');2const langs = extractLangs('en-US');3console.log(langs);4const { extractLangs } = require('playwright/lib/server/common/supplements.js');5const langs = extractLangs('en-US');6const context = await browser.newContext({ acceptLanguages: langs });7const page = await context.newPage();

StackOverFlow community discussions

Questions

Discussion

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

Running Playwright in Azure Function

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

firefox browser does not start in playwright

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

firefox browser does not start 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

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

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

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

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 Refresh Page Using Selenium C# [Complete Tutorial]

When working on web automation with Selenium, I encountered scenarios where I needed to refresh pages from time to time. When does this happen? One scenario is that I needed to refresh the page to check that the data I expected to see was still available even after refreshing. Another possibility is to clear form data without going through each input individually.

How To Handle Multiple Windows In Selenium Python

Automating testing is a crucial step in the development pipeline of a software product. In an agile development environment, where there is continuous development, deployment, and maintenance of software products, automation testing ensures that the end software products delivered are error-free.

Why Agile Is Great for Your Business

Agile project management is a great alternative to traditional methods, to address the customer’s needs and the delivery of business value from the beginning of the project. This blog describes the main benefits of Agile for both the customer and the business.

Guide To Find Index Of Element In List with Python Selenium

In an ideal world, you can test your web application in the same test environment and return the same results every time. The reality can be difficult sometimes when you have flaky tests, which may be due to the complexity of the web elements you are trying to perform an action on your test case.

40 Best UI Testing Tools And Techniques

A good User Interface (UI) is essential to the quality of software or application. A well-designed, sleek, and modern UI goes a long way towards providing a high-quality product for your customers − something that will turn them on.

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.