It’s been exactly one year since the last breaking change to React. Our next major release, React 16, will include some exciting improvements, including a complete rewrite of React’s internals. We take stability seriously, and are committed to bringing those improvements to all of our users with minimal effort.

To that end, today we’re releasing React 15.5.0.

New Deprecation Warnings

The biggest change is that we’ve extracted React.PropTypes and React.createClass into their own packages. Both are still accessible via the main React object, but using either will log a one-time deprecation warning to the console when in development mode. This will enable future code size optimizations.

These warnings will not affect the behavior of your application. However, we realize they may cause some frustration, particularly if you use a testing framework that treats console.error as a failure.

Adding new warnings is not something we do lightly. Warnings in React are not mere suggestions — they are integral to our strategy of keeping as many people as possible on the latest version of React. We never add warnings without providing an incremental path forward.

So while the warnings may cause frustration in the short-term, we believe prodding developers to migrate their codebases now prevents greater frustration in the future. Proactively fixing warnings ensures you are prepared for the next major release. If your app produces zero warnings in 15.5, it should continue to work in 16 without any changes.

For each of these new deprecations, we’ve provided a codemod to automatically migrate your code. They are available as part of the react-codemod project.

Migrating from React.PropTypes

Prop types are a feature for runtime validation of props during development. We’ve extracted the built-in prop types to a separate package to reflect the fact that not everybody uses them.

In 15.5, instead of accessing PropTypes from the main React object, install the prop-types package and import them from there:

import React from 'react' ; class Component extends React . Component { render ( ) { return < div > { this . props . text } </ div > ; } } Component . propTypes = { text : React . PropTypes . string . isRequired , } import React from 'react' ; import PropTypes from 'prop-types' ; class Component extends React . Component { render ( ) { return < div > { this . props . text } </ div > ; } } Component . propTypes = { text : PropTypes . string . isRequired , } ;

The codemod for this change performs this conversion automatically. Basic usage:

jscodeshift -t react-codemod/transforms/React-PropTypes-to-prop-types.js < path >

The propTypes , contextTypes , and childContextTypes APIs will work exactly as before. The only change is that the built-in validators now live in a separate package.

You may also consider using Flow to statically type check your JavaScript code, including React components.

Migrating from React.createClass

When React was initially released, there was no idiomatic way to create classes in JavaScript, so we provided our own: React.createClass .

Later, classes were added to the language as part of ES2015, so we added the ability to create React components using JavaScript classes. Along with function components, JavaScript classes are now the preferred way to create components in React.

For your existing createClass components, we recommend that you migrate them to JavaScript classes. However, if you have components that rely on mixins, converting to classes may not be immediately feasible. If so, create-react-class is available on npm as a drop-in replacement:

var React = require ( 'react' ) ; var Component = React . createClass ( { mixins : [ MixinA ] , render ( ) { return < Child /> ; } } ) ; var React = require ( 'react' ) ; var createReactClass = require ( 'create-react-class' ) ; var Component = createReactClass ( { mixins : [ MixinA ] , render ( ) { return < Child /> ; } } ) ;

Your components will continue to work the same as they did before.

The codemod for this change attempts to convert a createClass component to a JavaScript class, with a fallback to create-react-class if necessary. It has converted thousands of components internally at Facebook.

Basic usage:

jscodeshift -t react-codemod/transforms/class.js path/to/components

Discontinuing support for React Addons

We’re discontinuing active maintenance of React Addons packages. In truth, most of these packages haven’t been actively maintained in a long time. They will continue to work indefinitely, but we recommend migrating away as soon as you can to prevent future breakages.

react-addons-create-fragment – React 16 will have first-class support for fragments, at which point this package won’t be necessary. We recommend using arrays of keyed elements instead.

– React 16 will have first-class support for fragments, at which point this package won’t be necessary. We recommend using arrays of keyed elements instead. react-addons-css-transition-group - Use react-transition-group/CSSTransitionGroup instead. Version 1.1.1 provides a drop-in replacement.

- Use react-transition-group/CSSTransitionGroup instead. Version 1.1.1 provides a drop-in replacement. react-addons-linked-state-mixin - Explicitly set the value and onChange handler instead.

- Explicitly set the and handler instead. react-addons-pure-render-mixin - Use React.PureComponent instead.

- Use instead. react-addons-shallow-compare - Use React.PureComponent instead.

- Use instead. react-addons-transition-group - Use react-transition-group/TransitionGroup instead. Version 1.1.1 provides a drop-in replacement.

- Use react-transition-group/TransitionGroup instead. Version 1.1.1 provides a drop-in replacement. react-addons-update - Use immutability-helper instead, a drop-in replacement.

- Use immutability-helper instead, a drop-in replacement. react-linked-input - Explicitly set the value and onChange handler instead.

We’re also discontinuing support for the react-with-addons UMD build. It will be removed in React 16.

React Test Utils

Currently, the React Test Utils live inside react-addons-test-utils . As of 15.5, we’re deprecating that package and moving them to react-dom/test-utils instead:

import TestUtils from 'react-addons-test-utils' ; import TestUtils from 'react-dom/test-utils' ;

This reflects the fact that what we call the Test Utils are really a set of APIs that wrap the DOM renderer.

The exception is shallow rendering, which is not DOM-specific. The shallow renderer has been moved to react-test-renderer/shallow .

import { createRenderer } from 'react-addons-test-utils' ; import { createRenderer } from 'react-test-renderer/shallow' ;

Acknowledgements

A special thank you to these folks for transferring ownership of npm package names:

Installation

We recommend using Yarn or npm for managing front-end dependencies. If you’re new to package managers, the Yarn documentation is a good place to get started.

To install React with Yarn, run:

yarn add react@^15.5.0 react-dom@^15.5.0

To install React with npm, run:

npm install --save react@^15.5.0 react-dom@^15.5.0

We recommend using a bundler like webpack or Browserify so you can write modular code and bundle it together into small packages to optimize load time.

Remember that by default, React runs extra checks and provides helpful warnings in development mode. When deploying your app, make sure to compile it in production mode.

In case you don’t use a bundler, we also provide pre-built bundles in the npm packages which you can include as script tags on your page:

React

Dev build with warnings: react/dist/react.js

Minified build for production: react/dist/react.min.js

Dev build with warnings: react/dist/react.js Minified build for production: react/dist/react.min.js React with Add-Ons

Dev build with warnings: react/dist/react-with-addons.js

Minified build for production: react/dist/react-with-addons.min.js

Dev build with warnings: react/dist/react-with-addons.js Minified build for production: react/dist/react-with-addons.min.js React DOM (include React in the page before React DOM)

Dev build with warnings: react-dom/dist/react-dom.js

Minified build for production: react-dom/dist/react-dom.min.js

(include React in the page before React DOM) Dev build with warnings: react-dom/dist/react-dom.js Minified build for production: react-dom/dist/react-dom.min.js React DOM Server (include React in the page before React DOM Server)

Dev build with warnings: react-dom/dist/react-dom-server.js

Minified build for production: react-dom/dist/react-dom-server.min.js

We’ve also published version 15.5.0 of the react , react-dom , and addons packages on npm and the react package on bower.

Changelog

React

Added a deprecation warning for React.createClass . Points users to create-react-class instead. (@acdlite in d9a4fa4)

. Points users to create-react-class instead. (@acdlite in d9a4fa4) Added a deprecation warning for React.PropTypes . Points users to prop-types instead. (@acdlite in 043845c)

. Points users to prop-types instead. (@acdlite in 043845c) Fixed an issue when using ReactDOM together with ReactDOMServer . (@wacii in #9005)

together with . (@wacii in #9005) Fixed issue with Closure Compiler. (@anmonteiro in #8895)

Another fix for Closure Compiler. (@Shastel in #8882)

Added component stack info to invalid element type warning. (@n3tr in #8495)

React DOM

Fixed Chrome bug when backspacing in number inputs. (@nhunzaker in #7359)

Added react-dom/test-utils , which exports the React Test Utils. (@bvaughn)

React Test Renderer

Fixed bug where componentWillUnmount was not called for children. (@gre in #8512)

was not called for children. (@gre in #8512) Added react-test-renderer/shallow , which exports the shallow renderer. (@bvaughn)

React Addons