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 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.

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:

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

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

With React Proxy:

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
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 causes its identity to change

Contributing

Clone the repository
Run npm install
Run npm run test:watch
Take a look at the existing tests
Add tests for the failing case you aim to fix and make them pass
Submit a PR!

License

MIT

gaearon/react-proxy