react/packages/react-codemod

react-codemod

This repository contains a collection of codemod scripts based for use with JSCodeshift that help update React APIs.

Setup & Run

• npm install -g jscodeshift
• git clone https://github.com/facebook/react.git or download a zip file from https://github.com/facebook/react/archive/master.zip
• jscodeshift -t <codemod-script> <file>
• Use the -d option for a dry-run and use -p to print the output for comparison

Included Scripts

findDOMNode updates this.getDOMNode() or this.refs.foo.getDOMNode() calls inside of React.createClass components to React.findDOMNode(foo). Note that it will only look at code inside of React.createClass calls and only update calls on the component instance or its refs. You can use this script to update most calls to getDOMNode and then manually go through the remaining calls.

• jscodeshift -t react/packages/react-codemod/transforms/findDOMNode.js <file>

react-to-react-dom updates code for the split of the react and react-dom packages (e.g., React.render to ReactDOM.render). It looks for require('react') and replaces the appropriate property accesses using require('react-dom'). It does not support ES6 modules or other non-CommonJS systems. We recommend performing the findDOMNode conversion first.

• jscodeshift -t react/packages/react-codemod/transforms/react-to-react-dom.js <file>
• After running the automated codemod, you may want to run a regex-based find-and-replace to remove extra whitespace between the added requires, such as codemod.py -m -d src --extensions js '(var React\s*=\s*require\(.react.\);)\n\n(\s*var ReactDOM)' '\1\n\2' using https://github.com/facebook/codemod.

pure-render-mixin removes PureRenderMixin and inlines shouldComponentUpdate so that the ES2015 class transform can pick up the React component and turn it into an ES2015 class. NOTE: This currently only works if you are using the master version (>0.13.1) of React as it is using React.addons.shallowCompare

• jscodeshift -t react/packages/react-codemod/transforms/pure-render-mixin.js <file>
• If --mixin-name=<name> is specified it will look for the specified name instead of PureRenderMixin. Note that it is not possible to use a namespaced name for the mixin. mixins: [React.addons.PureRenderMixin] will not currently work.

class transforms React.createClass calls into ES2015 classes.

• jscodeshift -t react/packages/react-codemod/transforms/class.js <file>
• If --no-super-class is specified it will not extend React.Component if setState and forceUpdate aren't being called in a class. We do recommend always extending from React.Component, especially if you are using or planning to use Flow. Also make sure you are not calling setState anywhere outside of your component.

These three scripts take an option --no-explicit-require if you don't have a require('React') statement in your code files and if you access React as a global.

Explanation of the ES2015 class transform

• Ignore components with calls to deprecated APIs. This is very defensive, if the script finds any identifiers called isMounted, getDOMNode, replaceProps, replaceState or setProps it will skip the component.
• Replaces var A = React.createClass(spec) with class A (extends React.Component) {spec}.
• Pulls out all statics defined on statics plus the few special cased statics like propTypes, childContextTypes, contextTypes and displayName and assigns them after the class is created. class A {}; A.foo = bar;
• Takes getDefaultProps and inlines it as a static defaultProps. If getDefaultProps is defined as a function with a single statement that returns an object, it optimizes and transforms getDefaultProps() { return {foo: 'bar'}; } into A.defaultProps = {foo: 'bar'};. If getDefaultProps contains more than one statement it will transform into a self-invoking function like this: A.defaultProps = function() {…}();. Note that this means that the function will be executed only a single time per app-lifetime. In practice this hasn't caused any issues – getDefaultProps should not contain any side-effects.
• Binds class methods to the instance if methods are referenced without being called directly. It checks for this.foo but also traces variable assignments like var self = this; self.foo. It does not bind functions from the React API and ignores functions that are being called directly (unless it is both called directly and passed around to somewhere else)
• Creates a constructor if necessary. This is necessary if either getInitialState exists in the React.createClass spec OR if functions need to be bound to the instance.
• When --no-super-class is passed it only optionally extends React.Component when setState or forceUpdate are used within the class.

The constructor logic is as follows:

• Call super(props, context) if the base class needs to be extended.
• Bind all functions that are passed around, like this.foo = this.foo.bind(this)
• Inline getInitialState (and remove getInitialState from the spec). It also updates access of this.props.foo to props.foo and adds props as argument to the constructor. This is necessary in the case when the base class does not need to be extended where this.props will only be set by React after the constructor has been run.
• Changes return StateObject from getInitialState to assign this.state directly.

Recast Options

Options to recast's printer can be provided through the printOptions command line argument

• jscodeshift -t transform.js <file> --printOptions='{"quote":"double"}'