react.dev/docs/09-reference.md

id	title	layout	permalink	prev
reference	Reference	docs	reference.html	tooling-integration.html

Examples

Production Apps

• All of Instagram.com is built on React.
• Many components on Facebook.com, including the commenting interface, ads creation flows, and page insights.
• Khan Academy is using React for its question editor.

Sample Code

• We've included a step-by-step comment box tutorial.
• The React starter kit includes several examples which you can view online in our GitHub repository.
• reactapp is a simple app template to get you up-and-running quickly with React.
• React one-hour email goes step-by-step from a static HTML mock to an interactive email reader (written in just one hour!)
• Rendr + React app template demonstrates how to use React's server rendering capabilities.

API

React

React is the entry point to the React framework. If you're using one of the prebuilt packages it's available as a global; if you're using CommonJS modules you can require() it.

React.DOM

React.DOM provides all of the standard HTML tags needed to build a React app. You generally don't use it directly; instead, just include it as part of the /** @jsx React.DOM */ docblock.

React.initializeTouchEvents

initializeTouchEvents(boolean shouldUseTouch)

Configure React's event system to handle touch events on mobile devices.

React.createClass

function createClass(object specification)

Creates a component given a specification. A component implements a render method which returns one single child. That child may have an arbitrarily deep child structure. One thing that makes components different than a standard prototypal classes is that you don't need to call new on them. They are convenience wrappers that construct backing instances (via new) for you.

React.renderComponent

ReactComponent renderComponent(ReactComponent container, DOMElement container)

Renders a React component into the DOM in the supplied container.

If the React component was previously rendered into container, this will perform an update on it and only mutate the DOM as necessary to reflect the latest React component.

React.unmountAndReleaseReactRootNode

unmountAndReleaseReactRootNode(DOMElement container)

Remove a mounted React component from the DOM and clean up its event handlers and state.

React.renderComponentToString

renderComponentToString(ReactComponent component, function callback)

Render a component to its initial HTML. This should only be used on the server. React will call callback with an HTML string when the markup is ready. You can use this method to create static site generators, or you can generate HTML on the server and send it down to have a very fast initial page load. If you call React.renderComponent() on a node that already has this server-rendered markup, React will preserve it and only attach event handlers, allowing you to have a very performant first-load experience.

AbstractEvent

Your event handlers will be passed instances of AbstractEvent, a cross-browser wrapper around the browser's native event. It has the same interface as the browser's native event (such as stopPropagation() and preventDefault()) except they work exactly the same across all browsers.

If you find that you need the underlying browser event for some reason, simply use the nativeEvent attribute to get it.

ReactComponent

Component classses created by createClass() return instances of ReactComponent when called. Most of the time when you're using React you're either creating or consuming ReactComponents.

getDOMNode

DOMElement getDOMNode()

If this component has been mounted into the DOM, this returns the corresponding native browser DOM element. This method is useful for reading values out of the DOM, such as form field values and performing DOM measurements.

setProps

setProps(object nextProps)

When you're integrating with an external JavaScript application you may want to signal a change to a React component rendered with renderComponent(). Simply call setProps() to change its properties and trigger a re-render.

Note:

This method can only be called on a root-level component. That is, it's only available on the component passed directly to renderComponent() and none of its children. If you're inclined to use setProps() on a child component, instead take advantage of reactive updates and pass the new prop to the child component when it's created in render().

replaceProps

replaceProps(object nextProps)

Like setProps() but deletes any pre-existing props that are not in nextProps.

transferPropsTo

ReactComponent transferPropsTo(ReactComponent targetComponent)

Transfer properties from this component to a target component that have not already been set on the target component. This is usually used to pass down properties to the returned root component. targetComponent, now updated with some new props is returned as a convenience.

setState

setState(object nextState[, function callback])

Merges nextState with the current state. This is the primary method you use to trigger UI updates from event handlers and server request callbacks. In addition, you can supply an optional callback function that is executed once setState is completed.

Note:

NEVER mutate this.state directly. As calling setState() afterwards may replace the mutation you made. Treat this.state as if it were immutable.

Note:

setState() does not immediately mutate this.state but creates a pending state transition. Accessing this.state after calling this method can potentially return the existing value.

Note:

There is no guarantee of synchronous operation of calls to setState and calls may be batched for performance gains.

replaceState

replaceState(object nextState[, function callback])

Like setState() but deletes any pre-existing state keys that are not in nextState.

forceUpdate()

forceUpdate([function callback])

If your render() method reads from something other than this.props or this.state you'll need to tell React when it needs to re-run render(). Use forceUpdate() to cause React to automatically re-render. This will cause render() to be called on the component and all of its children but React will only update the DOM if the markup changes.

Normally you should try to avoid all uses of forceUpdate() and only read from this.props and this.state in render(). This makes your application much simpler and more efficient.

Note:

There is no guarantee of synchronous operation of calls to forceUpdate and calls may be batched for performance gains.

Lifecycle methods

object getInitialState()
componentWillMount()
componentDidMount(DOMElement domNode)
componentWillReceiveProps(object nextProps)
boolean shouldComponentUpdate(object nextProps, object nextState)
componentWillUpdate(object nextProps, object nextState)
ReactComponent render()
componentDidUpdate(object prevProps, object prevState, DOMElement domNode)
componentWillUnmount()

See the working with the browser documentation for more details on these lifecycle methods.

DOM Differences

React has implemented a browser-independent events and DOM system for performance and cross-browser compatibility reasons. We took the opportunity to clean up a few rough edges in browser DOM implementations.

• All events (including submit) bubble correctly per the W3C spec
• All event objects conform to the W3C spec
• All DOM properties and attributes (including event handlers) should be camelCased to be consistent with standard JavaScript style. We intentionally break with the spec here, since the spec is inconsistent.
• The style attribute accepts a JavaScript object with camelCased properties rather than a CSS string. This is consistent with the DOM style JavaScript property, is more efficient, and prevents XSS security holes.
• onChange behaves as you would expect it to: whenever a form field is changed this event is fired rather than inconsistently on blur. We intentionally break from existing browser behavior because onChange is a misnomer for its behavior and React relies on this event to react to user input in real time.