# React Proxy [![build status](https://img.shields.io/travis/gaearon/react-proxy/master.svg?style=flat-square)](https://travis-ci.org/gaearon/react-proxy) [![npm version](https://img.shields.io/npm/v/react-proxy.svg?style=flat-square)](https://www.npmjs.com/package/react-proxy)

A generic React component proxy used as the new engine by React Hot Loader. 

## 1.x and 2.x

You are looking at the README from the 1.x branch that is widely in use. However we intend to gradually transition projects such as `react-transform-hmr` to use [2.x that is being developed in master](https://github.com/gaearon/react-proxy/tree/master) instead. Currently we mirror all releases on both branches.


## Requirements

* React 0.13+

## Usage

Intended to be used from hot reloading tools like React Hot Loader.  
If you’re an application developer, it’s unlikely you’ll want to use it directly.

```js
import React, { Component } from 'react';

class ComponentVersion1 extends Component {
  render() {
    return <div>Before hot update.</div>;
  }
}

class ComponentVersion2 extends Component {
  render() {
    return <div>After hot update.</div>;
  }
}
```

Without React Proxy:

```js
const rootEl = document.getElementById('root');
React.render(<ComponentVersion1 />, rootEl);

// Will reset state and kill DOM :-(
React.render(<ComponentVersion2 />, rootEl);
```

With React Proxy:

```js
import { createProxy, getForceUpdate } from 'react-proxy';

// Create a proxy object, given the initial React component class.
const proxy = createProxy(ComponentVersion1);

// Obtain a React class that acts exactly like the initial version.
// This is what we'll use in our app instead of the real component class.
const Proxy = proxy.get();

// Render the component (proxy, really).
React.render(<Proxy />, rootEl);

// Point the proxy to the new React component class by calling update().
// Instances will stay mounted and their state will be intact, but their methods will be updated.
// The update() method returns an array of mounted instances so we can do something with them.
const mountedInstances = proxy.update(ComponentVersion2);

// React Proxy also provides us with getForceUpdate() method that works even if the component
// instance doesn't descend from React.Component, and doesn't have a forceUpdate() method.
const forceUpdate = getForceUpdate(React);

// Force-update all the affected instances!
mountedInstances.forEach(forceUpdate);
```

## Features

* Supports both classic (`React.createClass()`) and modern (ES6 classes) style
* Supports classes that don’t descend from `React.Component`
* Supports classes with strict `shouldComponentUpdate`
* Supports inherited and base classes (although you shouldn’t use inheritance with React)
* Supports classic `createClass()` autobinding and modern [`autobind-decorator`](https://github.com/andreypopp/autobind-decorator)
* Contains an extensive test suite to avoid regressions
* Preserves `displayName`
* Preserves enumerability and writability of methods
* Preserves `toString()` of methods
* Replaces instance getters and setters
* Replaces instance methods preserving their identity
* Replaces bound instance methods preserving their identity
* Because identity is preserved, instance methods already scheduled for `setInterval` or `setTimeout` are updated
* Replaces static getters and setters
* Replaces unbound static methods
* Replaces static properties unless they were overwritten by code

## Known Limitations

* Does not replace ES7 instance properties
* Does not replace bound static methods
* Replacing a method using [`autobind-decorator`](https://github.com/andreypopp/autobind-decorator) causes its identity to change

## Contributing

1. Clone the repository
2. Run `npm install`
3. Run `npm run test:watch`
4. Take a look at the existing tests
5. Add tests for the failing case you aim to fix and make them pass
6. Submit a PR!

## License

MIT