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Library

Playwright Library provides unified APIs for launching and interacting with browsers, while Playwright Test provides all this plus a fully managed end-to-end Test Runner and experience.

Under most circumstances, for end-to-end testing, you'll want to use @playwright/test (Playwright Test), and not playwright (Playwright Library) directly. To get started with Playwright Test, follow its Getting Started Guide.

When Should Playwright Library Be Used Directly?​

  • creating an integration for a third party test runner (e.g. the third-party runner plugins listed here are built on top of Playwright Library)
  • automation and scraping

Differences​

Library Example​

The following is an example of using the Playwright Library directly to launch Chromium, go to a page, and check its title:

import playwright, { devices } from 'playwright';

(async () => {
  // Setup
  const browser = await playwright.chromium.launch();
  const context = await browser.newContext(devices['iPhone 11']);
  const page = await context.newPage();

  // The actual interesting bit
  await context.route('**.jpg', route => route.abort());
  await page.goto('https://example.com/');

  assert(await page.title() === 'Example'); // 👎 not a Web First assertion

  // Teardown
  await context.close();
  await browser.close();
})()

Run via:

node ./my-script.ts

Test Example​

A test to achieve similar behavior, would look like:

import { expect, test, devices } from '@playwright/test';

test.use(devices['iPhone 11']);

test('should be titled', async ({ page, context }) => {
  await context.route('**.jpg', route => route.abort());
  await page.goto('https://example.com/');

  await expect(page).toHaveTitle('Example');
});

Run via:

npx playwright test

Key Differences​

The key differences to note are as follows:

LibraryTest
Installationnpm install playwrightnpm init playwright@latest (note install vs. init)
Install browsersChromium, Firefox, WebKit are installed by defaultnpx playwright install or npx playwright install chromium for a single one
import/require nameplaywright@playwright/test
InitializationExplicitly need to:
  1. Pick a browser to use (e.g. chromium)
  2. Create browser (browserType.launch([options]))
  3. Create a context (browser.newContext([options])), and pass any context options explcitly (e.g. devices['iPhone 11']
  4. Create a page (browserContext.newPage())
An isolated page and context are provided to each test out-of the box (along with any other built-in fixtures). No explicit creation. If referenced by the test in it's arguments, the Test Runner will create them for the test. (i.e. lazy-initialization)
AssertionsNo built-in Web-First AssertionsWeb-First assertions like: which auto-wait and retry for the condition to be met.
CleanupExplicitly need to:
  1. Close context (browserContext.close())
  2. Close browser (browser.close())
No explicit close of built-in fixtures; the Test Runner will take care of it.
RunningWhen using the Library, you run the code as a node script (possibly with some compilation first).When using the Test Runner, you use the npx playwright test command. Along with your config), the Test Runner handles any compilation and choosing what to run and how to run it.

In addition to the above, Playwright Test—as a full-featured Test Runner—includes:

Usage​

Use npm or Yarn to install Playwright library in your Node.js project. See system requirements.

npm i -D playwright

This single command downloads the Playwright NPM package and browser binaries for Chromium, Firefox and WebKit. To modify this behavior see managing browsers.

Once installed, you can require Playwright in a Node.js script, and launch any of the 3 browsers (chromium, firefox and webkit).

const { chromium } = require('playwright');

(async () => {
  const browser = await chromium.launch();
  // Create pages, interact with UI elements, assert values
  await browser.close();
})();

Playwright APIs are asynchronous and return Promise objects. Our code examples use the async/await pattern to ease readability. The code is wrapped in an unnamed async arrow function which is invoking itself.

(async () => { // Start of async arrow function
  // Function code
  // ...
})(); // End of the function and () to invoke itself

First script​

In our first script, we will navigate to whatsmyuseragent.org and take a screenshot in WebKit.

const { webkit } = require('playwright');

(async () => {
  const browser = await webkit.launch();
  const page = await browser.newPage();
  await page.goto('http://whatsmyuseragent.org/');
  await page.screenshot({ path: `example.png` });
  await browser.close();
})();

By default, Playwright runs the browsers in headless mode. To see the browser UI, pass the headless: false flag while launching the browser. You can also use slowMo to slow down execution. Learn more in the debugging tools section.

firefox.launch({ headless: false, slowMo: 50 });

Record scripts​

Command line tools can be used to record user interactions and generate JavaScript code.

npx playwright codegen wikipedia.org

TypeScript support​

Playwright includes built-in support for TypeScript. Type definitions will be imported automatically. It is recommended to use type-checking to improve the IDE experience.

In JavaScript​

Add the following to the top of your JavaScript file to get type-checking in VS Code or WebStorm.

//@ts-check
// ...

Alternatively, you can use JSDoc to set types for variables.

/** @type {import('playwright').Page} */
let page;

In TypeScript​

TypeScript support will work out-of-the-box. Types can also be imported explicitly.

let page: import('playwright').Page;