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

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