joshblack / react-proxy

Proxies React components without unmounting or losing their state

React Proxy

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

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