React-ES5-To-ES6-Checklist

ECMAScript2015(ES6) is the latest version of the ECMAScript standard.

React is a declarative, efficient, and flexible JavaScript library for building user interfaces.

In the earlier days of React development, many programms were written in ES5. Howerver, as ES6 is more widely accepted now and with the help of transplier tools like Babel, we can gradually retire some ES5 code and adopt some ES6 new features in React development.

Here is a check list to help you translate your ES5 code to newer version in React. You are welcome to contribute with more items provided below.

Quick links

• require => import
• createClass => extends React.Component
• module.exports => export default
• name: function() => name()
• getDefaultProps and propTypes
• getInitialState
• Destructuring & spread attributes

require-to-import

ES5

//ES5
var React = require("react");  
var PropTypes = React.PropTypes;

ES6

import React, { Component, PropTypes } from 'react';

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createClass-to-extends

ES5

var Mycomponent = React.createClass({
  render: function() {
    return (
      <div>ES5</div>
    );
  },
});

ES6

class Mycomponent extends React.Component {
  render() {
    return (
      <div>ES6</div>
    );
  }
}

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module-exports-to-export-default

ES5

var Mycomponent = React.createClass({
  render: function() {
    return (
      <div>ES5</div>
    );
  },
});

module.exports = Mycomponent;

ES6

export default class Mycomponent extends React.Component {
  render() {
    return (
      <div>ES6</div>
    );
  }
}

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functions

ES5

var Mycomponent = React.createClass({
  componentWillMount: function(){

  },
  render: function() {
    return (
      <div>ES5</div>
    );
  },
});

module.exports = Mycomponent;

ES6

export default class Mycomponent extends React.Component {
  componentWillMount() {

  }
  render() {
    return (
      <div>ES6</div>
    );
  }
}

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getDefaultProps-and-propTypes

ES5

var Video = React.createClass({
    getDefaultProps: function() {
        return {
            autoPlay: false,
            maxLoops: 10,
        };
    },
    propTypes: {
        autoPlay: React.PropTypes.bool.isRequired,
        maxLoops: React.PropTypes.number.isRequired,
        posterFrameSrc: React.PropTypes.string.isRequired,
        videoSrc: React.PropTypes.string.isRequired,
    },
    render: function() {
        return (
            <View />
        );
    },
});

ES6

class Video extends React.Component {
  render() {
      return (
          <View />
      );
  }
}
Video.defaultProps = {
    autoPlay: false,
    maxLoops: 10,
};
Video.propTypes = {
    autoPlay: React.PropTypes.bool.isRequired,
    maxLoops: React.PropTypes.number.isRequired,
    posterFrameSrc: React.PropTypes.string.isRequired,
    videoSrc: React.PropTypes.string.isRequired,
};

ES7:

class Video extends React.Component {
  static defaultProps = {
    autoPlay: false,
    maxLoops: 10,
  }
  static propTypes = {
    autoPlay: React.PropTypes.bool.isRequired,
    maxLoops: React.PropTypes.number.isRequired,
    posterFrameSrc: React.PropTypes.string.isRequired,
    videoSrc: React.PropTypes.string.isRequired,
  }
  state = {
    loopsRemaining: this.props.maxLoops,
  }
}

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getInitialState

ES5

var Header = React.createClass({
  getInitialState: function() {
    return {
      title: this.props.title
    };
  },
});

ES6

export default class Header extends Component {
  constructor(props) {
    super(props);
      this.state = {
        title: props.title
      };
    }
}

ES7

export default class Header extends Component {
  state = {
    title: this.props.title
  };
    
  // followed by constructor...
}

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Destructuring-and-spread-attributes

class AutoloadingPostsGrid extends React.Component {
  render() {
    var {
      className,
      ...others,  // contains all properties of this.props except for className
    } = this.props;
    return (
      <div className={className}>
        <PostsGrid {...others} />
        <button onClick={this.handleLoadMoreClick}>Load more</button>
      </div>
    );
  }
}

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Reference

• React
• Babel
• ECMAScript 6 support in Mozilla
• React on ES6+
• Converting React project from ES5 to ES6
• React/React Native 的ES5 ES6写法对照表

Roadmap

• Include all ES5 to ES6+ instructions for React
• We may Implement ESlint plugin like ESlint-Plugin-React-5-to-6
• We may Include instructions for configuring Babel with different stages

License

MIT