react

What are react's main functionalities?

class Welcome extends React.Component {
  render() {
    return <h1>Hello, {this.props.name}</h1>;
  }
}
ReactDOM.render(<Welcome name='Jane' />, document.getElementById('root'));

class Counter extends React.Component {
  constructor(props) {
    super(props);
    this.state = { count: 0 };
  }
  increment = () => {
    this.setState({ count: this.state.count + 1 });
  };
  render() {
    return (
      <div>
        <p>{this.state.count}</p>
        <button onClick={this.increment}>Increment</button>
      </div>
    );
  }
}

class Timer extends React.Component {
  componentDidMount() {
    this.timerID = setInterval(() => this.tick(), 1000);
  }
  componentWillUnmount() {
    clearInterval(this.timerID);
  }
  tick() {
    this.setState({
      date: new Date()
    });
  }
  render() {
    return (
      <div>
        <h2>It is {this.state.date.toLocaleTimeString()}.</h2>
      </div>
    );
  }
}

import { useState, useEffect } from 'react';

function Example() {
  const [count, setCount] = useState(0);

  useEffect(() => {
    document.title = `You clicked ${count} times`;
  });

  return (
    <div>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>
        Click me
      </button>
    </div>
  );
}

0.12.0 (October 28, 2014)

React Core

Breaking Changes

• key and ref moved off props object, now accessible on the element directly
• React is now BSD licensed with accompanying Patents grant
• Default prop resolution has moved to Element creation time instead of mount time, making them effectively static
• React.__internals is removed - it was exposed for DevTools which no longer needs access
• Composite Component functions can no longer be called directly - they must be wrapped with React.createFactory first. This is handled for you when using JSX.

New Features

• Spread operator ({...}) introduced to deprecate this.transferPropsTo
• Added support for more HTML attributes: acceptCharset, classID, manifest

Deprecations

• React.renderComponent --> React.render
• React.renderComponentToString --> React.renderToString
• React.renderComponentToStaticMarkup --> React.renderToStaticMarkup
• React.isValidComponent --> React.isValidElement
• React.PropTypes.component --> React.PropTypes.element
• React.PropTypes.renderable --> React.PropTypes.node
• DEPRECATED React.isValidClass
• DEPRECATED instance.transferPropsTo
• DEPRECATED Returning false from event handlers to preventDefault
• DEPRECATED Convenience Constructor usage as function, instead wrap with React.createFactory
• DEPRECATED use of key={null} to assign implicit keys

Bug Fixes

• Better handling of events and updates in nested results, fixing value restoration in "layered" controlled components
• Correctly treat event.getModifierState as case sensitive
• Improved normalization of event.charCode
• Better error stacks when involving autobound methods
• Removed DevTools message when the DevTools are installed
• Correctly detect required language features across browsers
• Fixed support for some HTML attributes:
  • list updates correctly now
  • scrollLeft, scrollTop removed, these should not be specified as props
• Improved error messages

React With Addons

New Features

• React.addons.batchedUpdates added to API for hooking into update cycle

Breaking Changes

• React.addons.update uses assign instead of copyProperties which does hasOwnProperty checks. Properties on prototypes will no longer be updated correctly.

Bug Fixes

• Fixed some issues with CSS Transitions

JSX

Breaking Changes

• Enforced convention: lower case tag names are always treated as HTML tags, upper case tag names are always treated as composite components
• JSX no longer transforms to simple function calls

New Features

• @jsx React.DOM no longer required
• spread ({...}) operator introduced to allow easier use of props

Bug Fixes

• JSXTransformer: Make sourcemaps an option when using APIs directly (eg, for react-rails)