playwright/docs/src/library-js.md

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---
id: library
title: "Playwright Library"
---
Playwright can either be used as a part of the [Playwright Test](./intro.md), or as a Playwright Library (this guide). If you are working on an application that utilizes Playwright capabilities or you are using Playwright with another test runner, read on.
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<!-- TOC -->
- [Release notes](./release-notes.md)
## Usage
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Use npm or Yarn to install Playwright library in your Node.js project. See [system requirements](#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](#managing-browser-binaries).
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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 Interface [CLI](./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;
```
## System requirements
Playwright requires Node.js version 12 or above. The browser binaries for Chromium,
Firefox and WebKit work across the 3 platforms (Windows, macOS, Linux):
### Windows
Works with Windows and Windows Subsystem for Linux (WSL).
### macOS
Requires 10.14 (Mojave) or above.
### Linux
Depending on your Linux distribution, you might need to install additional
dependencies to run the browsers.
:::note
Only Ubuntu 18.04 and Ubuntu 20.04 are officially supported.
:::
See also in the [Command Line Interface](./cli.md#install-system-dependencies)
which has a command to install all necessary dependencies automatically for Ubuntu
LTS releases.