By Sophie Alpert·
We’re happy to announce the release of React 0.14 today! This release has a few major changes, primarily designed to simplify the code you write every day and to better support environments like React Native.
If you tried the release candidate, thank you – your support is invaluable and we’ve fixed a few bugs that you reported.
As with all of our releases, we consider this version to be stable enough to use in production and recommend that you upgrade in order to take advantage of our latest improvements.
Like always, we have a few breaking changes in this release. We know changes can be painful (the Facebook codebase has over 15,000 React components), so we always try to make changes gradually in order to minimize the pain.
If your code is free of warnings when running under React 0.13, upgrading should be easy. We have two new small breaking changes that didn’t give a warning in 0.13 (see below). Every new change in 0.14, including the major changes below, is introduced with a runtime warning and will work as before until 0.15, so you don’t have to worry about your app breaking with this upgrade.
For the two major changes which require significant code changes, we’ve included codemod scripts to help you upgrade your code automatically.
See the changelog below for more details.
We recommend using React from npm
and using a tool like browserify or webpack to build your code into a single bundle. To install the two packages:
npm install --save react react-dom
Remember that by default, React runs extra checks and provides helpful warnings in development mode. When deploying your app, set the NODE_ENV
environment variable to production
to use the production build of React which does not include the development warnings and runs significantly faster.
If you can’t use npm
yet, we provide pre-built browser builds for your convenience, which are also available in the react
package on bower.
As we look at packages like react-native, react-art, react-canvas, and react-three, it has become clear that the beauty and essence of React has nothing to do with browsers or the DOM.
To make this more clear and to make it easier to build more environments that React can render to, we’re splitting the main react
package into two: react
and react-dom
. This paves the way to writing components that can be shared between the web version of React and React Native. We don’t expect all the code in an app to be shared, but we want to be able to share the components that do behave the same across platforms.
The react
package contains React.createElement
, .createClass
, .Component
, .PropTypes
, .Children
, and the other helpers related to elements and component classes. We think of these as the isomorphic or universal helpers that you need to build components.
The react-dom
package has ReactDOM.render
, .unmountComponentAtNode
, and .findDOMNode
. In react-dom/server
we have server-side rendering support with ReactDOMServer.renderToString
and .renderToStaticMarkup
.
var React = require('react');var ReactDOM = require('react-dom');var MyComponent = React.createClass({render: function () {return <div>Hello World</div>;},});ReactDOM.render(<MyComponent />, node);
The old names will continue to work with a warning until 0.15 is released, and we’ve published the automated codemod script we used at Facebook to help you with this transition.
The add-ons have moved to separate packages as well:
react-addons-clone-with-props
react-addons-create-fragment
react-addons-css-transition-group
react-addons-linked-state-mixin
react-addons-perf
react-addons-pure-render-mixin
react-addons-shallow-compare
react-addons-test-utils
react-addons-transition-group
react-addons-update
ReactDOM.unstable_batchedUpdates
in react-dom
.For now, please use matching versions of react
and react-dom
(and the add-ons, if you use them) in your apps to avoid versioning problems.
The other big change we’re making in this release is exposing refs to DOM components as the DOM node itself. That means: we looked at what you can do with a ref
to a React DOM component and realized that the only useful thing you can do with it is call this.refs.giraffe.getDOMNode()
to get the underlying DOM node. Starting with this release, this.refs.giraffe
is the actual DOM node. Note that refs to custom (user-defined) components work exactly as before; only the built-in DOM components are affected by this change.
var Zoo = React.createClass({render: function () {return (<div>Giraffe name: <input ref="giraffe" /></div>);},showName: function () {// Previously: var input = this.refs.giraffe.getDOMNode();var input = this.refs.giraffe;alert(input.value);},});
This change also applies to the return result of ReactDOM.render
when passing a DOM node as the top component. As with refs, this change does not affect custom components.
With this change, we’re deprecating .getDOMNode()
and replacing it with ReactDOM.findDOMNode
(see below). If your components are currently using .getDOMNode()
, they will continue to work with a warning until 0.15.
In idiomatic React code, most of the components you write will be stateless, simply composing other components. We’re introducing a new, simpler syntax for these components where you can take props
as an argument and return the element you want to render:
// A function component using an ES2015 (ES6) arrow function:var Aquarium = (props) => {var fish = getFish(props.species);return <Tank>{fish}</Tank>;};// Or with destructuring and an implicit return, simply:var Aquarium = ({species}) => <Tank>{getFish(species)}</Tank>;// Then use: <Aquarium species="rainbowfish" />
These components behave just like a React class with only a render
method defined. Since no component instance is created for a function component, any ref
added to one will evaluate to null
. Function components do not have lifecycle methods, but you can set .propTypes
and .defaultProps
as properties on the function.
This pattern is designed to encourage the creation of these simple components that should comprise large portions of your apps. In the future, we’ll also be able to make performance optimizations specific to these components by avoiding unnecessary checks and memory allocations.
The react-tools
package and JSXTransformer.js
browser file have been deprecated. You can continue using version 0.13.3
of both, but we no longer support them and recommend migrating to Babel, which has built-in support for React and JSX.
React now supports two compiler optimizations that can be enabled in Babel 5.8.24 and newer. Both of these transforms should be enabled only in production (e.g., just before minifying your code) because although they improve runtime performance, they make warning messages more cryptic and skip important checks that happen in development mode, including propTypes.
Inlining React elements: The optimisation.react.inlineElements
transform converts JSX elements to object literals like {type: 'div', props: ...}
instead of calls to React.createElement
.
Constant hoisting for React elements: The optimisation.react.constantElements
transform hoists element creation to the top level for subtrees that are fully static, which reduces calls to React.createElement
and the resulting allocations. More importantly, it tells React that the subtree hasn’t changed so React can completely skip it when reconciling.
In almost all cases, we change our APIs gradually and warn for at least one release to give you time to clean up your code. These two breaking changes did not have a warning in 0.13 but should be easy to find and clean up:
React.initializeTouchEvents
is no longer necessary and has been removed completely. Touch events now work automatically.TestUtils.findAllInRenderedTree
and related helpers are no longer able to take a DOM component, only a custom component.These three breaking changes had a warning in 0.13, so you shouldn’t have to do anything if your code is already free of warnings:
props
object is now frozen, so mutating props after creating a component element is no longer supported. In most cases, React.cloneElement
should be used instead. This change makes your components easier to reason about and enables the compiler optimizations mentioned above.createFragment
helper to migrate, which now returns an array.classSet
has been removed. Use classnames instead.Each of these changes will continue to work as before with a new warning until the release of 0.15 so you can upgrade your code gradually.
Due to the DOM node refs change mentioned above, this.getDOMNode()
is now deprecated and ReactDOM.findDOMNode(this)
can be used instead. Note that in most cases, calling findDOMNode
is now unnecessary – see the example above in the “DOM node refs” section.
With each returned DOM node, we’ve added a getDOMNode
method for backwards compatibility that will work with a warning until 0.15. If you have a large codebase, you can use our automated codemod script to change your code automatically.
setProps
and replaceProps
are now deprecated. Instead, call ReactDOM.render again at the top level with the new props.
ES6 component classes must now extend React.Component
in order to enable stateless function components. The ES3 module pattern will continue to work.
Reusing and mutating a style
object between renders has been deprecated. This mirrors our change to freeze the props
object.
Add-Ons: cloneWithProps
is now deprecated. Use React.cloneElement
instead (unlike cloneWithProps
, cloneElement
does not merge className
or style
automatically; you can merge them manually if needed).
Add-Ons: To improve reliability, CSSTransitionGroup
will no longer listen to transition events. Instead, you should specify transition durations manually using props such as transitionEnterTimeout={500}
.
React.Children.toArray
which takes a nested children object and returns a flat array with keys assigned to each child. This helper makes it easier to manipulate collections of children in your render
methods, especially if you want to reorder or slice this.props.children
before passing it down. In addition, React.Children.map
now returns plain arrays too.console.error
instead of console.warn
for warnings so that browsers show a full stack trace in the console. (Our warnings appear when you use patterns that will break in future releases and for code that is likely to behave unexpectedly, so we do consider our warnings to be “must-fix” errors.)Symbol
in browsers that support it, in order to ensure that React never considers untrusted JSON to be a valid element. If this extra security protection is important to you, you should add a Symbol
polyfill for older browsers, such as the one included by Babel’s polyfill.capture
, challenge
, inputMode
, is
, keyParams
, keyType
, minLength
, summary
, wrap
. It also now supports these non-standard attributes: autoSave
, results
, security
.xlinkActuate
, xlinkArcrole
, xlinkHref
, xlinkRole
, xlinkShow
, xlinkTitle
, xlinkType
, xmlBase
, xmlLang
, xmlSpace
.image
SVG tag is now supported by React DOM.is="..."
attribute).audio
and video
tags: onAbort
, onCanPlay
, onCanPlayThrough
, onDurationChange
, onEmptied
, onEncrypted
, onEnded
, onError
, onLoadedData
, onLoadedMetadata
, onLoadStart
, onPause
, onPlay
, onPlaying
, onProgress
, onRateChange
, onSeeked
, onSeeking
, onStalled
, onSuspend
, onTimeUpdate
, onVolumeChange
, onWaiting
.shallowCompare
add-on has been added as a migration path for PureRenderMixin
in ES6 classes.CSSTransitionGroup
can now use custom class names instead of appending -enter-active
or similar to the transition name.document.body
directly as the container to ReactDOM.render
now gives a warning as doing so can cause problems with browser extensions that modify the DOM.<option>
elements with multiple text children properly and renders <select>
elements on the server with the correct option selected.React.createElement('DIV')
) no longer causes problems, though we continue to recommend lowercase for consistency with the JSX tag name convention (lowercase names refer to built-in components, capitalized names refer to custom components).animationIterationCount
, boxOrdinalGroup
, flexOrder
, tabSize
, stopOpacity
.Simulate.mouseEnter
and Simulate.mouseLeave
now work.