msw

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<h1 align="center">Mock Service Worker</h1>
<p align="center">The industry standard for API mocking in JavaScript.</p>

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## Features

- **Seamless**. A dedicated layer of requests interception at your disposal. Keep your application's code and tests unaware of whether something is mocked or not.
- **Deviation-free**. Request the same production resources and test the actual behavior of your app. Augment an existing API, or design it as you go when there is none.
- **Familiar & Powerful**. Use [Express](https://github.com/expressjs/express)-like routing syntax to intercept requests. Use parameters, wildcards, and regular expressions to match requests, and respond with necessary status codes, headers, cookies, delays, or completely custom resolvers.

---

> "_I found MSW and was thrilled that not only could I still see the mocked responses in my DevTools, but that the mocks didn't have to be written in a Service Worker and could instead live alongside the rest of my app. This made it silly easy to adopt. The fact that I can use it for testing as well makes MSW a huge productivity booster._"
>
> — [Kent C. Dodds](https://twitter.com/kentcdodds)

## Documentation

This README will give you a brief overview of the library, but there's no better place to start with Mock Service Worker than its official documentation.

- [Documentation](https://mswjs.io/docs)
- [**Quick start**](https://mswjs.io/docs/quick-start)
- [FAQ](https://mswjs.io/docs/faq)

## Examples

- See the list of [**Usage examples**](https://github.com/mswjs/examples)

## Courses

We've partnered with Egghead to bring you quality paid materials to learn the best practices of API mocking on the web. Please give them a shot! The royalties earned from them help sustain the project's development. Thank you.

- 🚀 [**Mocking REST and GraphQL APIs with Mock Service Worker**](https://egghead.io/courses/mock-rest-and-graphql-apis-with-mock-service-worker-8d471ece?af=8mci9b)
- 🔌 [Mocking (and testing) WebSocket APIs with Mock Service Worker](https://egghead.io/courses/mocking-websocket-apis-with-mock-service-worker-9933b7f5)

## Browser

- [Learn more about using MSW in a browser](https://mswjs.io/docs/integrations/browser)
- [`setupWorker` API](https://mswjs.io/docs/api/setup-worker)

### How does it work?

In-browser usage is what sets Mock Service Worker apart from other tools. Utilizing the [Service Worker API](https://developer.mozilla.org/en-US/docs/Web/API/Service_Worker_API), which can intercept requests for the purpose of caching, Mock Service Worker responds to intercepted requests with your mock definition on the network level. This way your application knows nothing about the mocking.

**Take a look at this quick presentation on how Mock Service Worker functions