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97 lines
2.9 KiB
Markdown
97 lines
2.9 KiB
Markdown
---
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id: library
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title: "Library"
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---
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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 -->
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- [Release notes](./release-notes.md)
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## Usage
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Use npm or Yarn to install Playwright library in your Node.js project. See [system requirements](./troubleshooting.md#system-requirements).
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```bash
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npm i -D playwright
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```
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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).
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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`).
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```js
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const { chromium } = require('playwright');
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(async () => {
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const browser = await chromium.launch();
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// Create pages, interact with UI elements, assert values
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await browser.close();
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})();
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```
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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.
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```js
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(async () => { // Start of async arrow function
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// Function code
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// ...
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})(); // End of the function and () to invoke itself
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```
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## First script
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In our first script, we will navigate to `whatsmyuseragent.org` and take a screenshot in WebKit.
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```js
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const { webkit } = require('playwright');
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(async () => {
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const browser = await webkit.launch();
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const page = await browser.newPage();
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await page.goto('http://whatsmyuseragent.org/');
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await page.screenshot({ path: `example.png` });
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await browser.close();
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})();
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```
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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).
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```js
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firefox.launch({ headless: false, slowMo: 50 });
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```
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## Record scripts
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[Command line tools](./cli.md) can be used to record user interactions and generate JavaScript code.
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```bash
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npx playwright codegen wikipedia.org
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```
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## TypeScript support
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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.
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### In JavaScript
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Add the following to the top of your JavaScript file to get type-checking in VS Code or WebStorm.
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```js
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//@ts-check
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// ...
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```
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Alternatively, you can use JSDoc to set types for variables.
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```js
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/** @type {import('playwright').Page} */
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let page;
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```
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### In TypeScript
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TypeScript support will work out-of-the-box. Types can also be imported explicitly.
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```js
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let page: import('playwright').Page;
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```
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