playwright/docs/src/library-js.md

---
id: library
title: "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 the [Getting Started Guide](./intro.md).

## Differences when using library

### Library Example

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


```js tab=js-ts
import { chromium, devices } from 'playwright';
import assert from 'node:assert';

(async () => {
  // Setup
  const browser = await 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 Domain'); // 👎 not a Web First assertion

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

```js tab=js-js
const assert = require('node:assert');
const { chromium, devices } = require('playwright');

(async () => {
  // Setup
  const browser = await 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 Domain'); // 👎 not a Web First assertion

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

Run it with `node my-script.js`.

### Test Example

A test to achieve similar behavior, would look like:

```js tab=js-ts
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');
});
```

```js tab=js-js
const { expect, test, devices } = require('@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 it with `npx playwright test`.

### Key Differences

The key differences to note are as follows:

| | Library | Test |
| - | - | - |
| Installation | `npm install playwright` | `npm init playwright@latest` - note `install` vs. `init` |
| Install browsers | Chromium, Firefox, WebKit are installed by default | `npx playwright install` or `npx playwright install chromium` for a single one |
| `import`/`require` name | `playwright` | `@playwright/test` |
| Initialization | Explicitly need to: <ol><li>Pick a browser to use, e.g. `chromium`</li><li>Launch browser with [`method: BrowserType.launch`]</li><li>Create a context with [`method: Browser.newContext`], <em>and</em> pass any context options explicitly, e.g. `devices['iPhone 11']`</li><li>Create a page with [`method: BrowserContext.newPage`]</li></ol> | An isolated `page` and `context` are provided to each test out-of the box, along with other [built-in fixtures](./test-fixtures.md#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) |
| Assertions | No built-in Web-First Assertions | [Web-First assertions](./test-assertions.md) like: <ul><li>[`method: PageAssertions.toHaveTitle`]</li><li>[`method: PageAssertions.toHaveScreenshot#1`]</li></ul> which auto-wait and retry for the condition to be met.|
| Cleanup | Explicitly need to: <ol><li>Close context with [`method: BrowserContext.close`]</li><li>Close browser with [`method: Browser.close`]</li></ol> | No explicit close of [built-in fixtures](./test-fixtures.md#built-in-fixtures); the Test Runner will take care of it.
| Running | When 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](./test-configuration.md), 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:

- [Configuration Matrix and Projects](./test-configuration.md): In the above example, in the Playwright Library version, if we wanted to run with a different device or browser, we'd have to modify the script and plumb the information through. With Playwright Test, we can just specify the [matrix of configurations](./test-configuration.md) in one place, and it will create run the one test under each of these configurations.
- [Parallelization](./test-parallel.md)
- [Web-First Assertions](./test-assertions.md)
- [Reporting](./test-reporters.md)
- [Retries](./test-retries.md)
- [Easily Enabled Tracing](./test-configuration.md#record-test-trace)
- and more…

## Usage

Use npm or Yarn to install Playwright library in your Node.js project. See [system requirements](./troubleshooting.md#system-requirements).

```bash
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](./browsers.md#managing-browser-binaries).

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

```js
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](https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Asynchronous/Async_await) to ease readability. The code is wrapped in an unnamed async arrow function which is invoking itself.

```js
(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.

```js
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](./debug.md).

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

## Record scripts

[Command line tools](./cli.md) can be used to record user interactions and generate JavaScript code.

```bash
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.

```js
//@ts-check
// ...
```

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

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

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

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