React is the entry point to the React library. If you're using one of the prebuilt packages it's available as a global; if you're using CommonJS modules you can
This is the base class for React Components when they're defined using ES6 classes. See Reusable Components for how to use ES6 classes with React. For what methods are actually provided by the base class, see the Component API.
ReactClass createClass(object specification)
Create a component class, 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 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.
For more information about the specification object, see Component Specs and Lifecycle.
ReactElement createElement( string/ReactClass type, [object props], [children ...] )
Create and return a new
ReactElement of the given type. The type argument can be either an
html tag name string (eg. 'div', 'span', etc), or a
ReactClass (created via
ReactElement cloneElement( ReactElement element, [object props], [children ...] )
Clone and return a new
element as the starting point. The resulting element will have the original element's props with the new props merged in shallowly. New children will replace existing children. Unlike
ref from the original element will be preserved. There is no special behavior for merging any props (unlike
cloneWithProps). See the v0.13 RC2 blog post for additional details.
factoryFunction createFactory( string/ReactClass type )
Return a function that produces ReactElements of a given type. Like
React.createElement, the type argument can be either an html tag name string (eg. 'div', 'span', etc), or a
boolean isValidElement(* object)
Verifies the object is a ReactElement.
React.DOM provides convenience wrappers around
React.createElement for DOM components. These should only be used when not using JSX. For example,
React.DOM.div(null, 'Hello World!')
React.PropTypes includes types that can be used with a component's
propTypes object to validate props being passed to your components. For more information about
propTypes, see Reusable Components.
React.Children provides utilities for dealing with the
this.props.children opaque data structure.
array React.Children.map(object children, function fn [, object thisArg])
fn on every immediate child contained within
this set to
children is a keyed fragment or array it will be traversed:
fn will never be passed the container objects. If children is
undefined rather than an array.
React.Children.forEach(object children, function fn [, object thisArg])
React.Children.map() but does not return an array.
number React.Children.count(object children)
Return the total number of components in
children, equal to the number of times that a callback passed to
forEach would be invoked.
object React.Children.only(object children)
Return the only child in
children. Throws otherwise.
array React.Children.toArray(object children)
children opaque data structure as a flat array with keys assigned to each child. Useful if you want to manipulate collections of children in your render methods, especially if you want to reorder or slice
this.props.children before passing it down.
React.Children.toArray()changes keys to preserve the semantics of nested arrays when flattening lists of children. That is,
toArrayprefixes each key in the returned array so that each element's key is scoped to the input array containing it.
react-dom package provides DOM-specific methods that can be used at the top level of your app and as an escape hatch to get outside of the React model if you need to. Most of your components should not need to use this module.
render( ReactElement element, DOMElement container, [function callback] )
If the ReactElement 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.
If the optional callback is provided, it will be executed after the component is rendered or updated.
ReactDOM.render()controls the contents of the container node you pass in. Any existing DOM elements inside are replaced when first called. Later calls use React’s DOM diffing algorithm for efficient updates.
ReactDOM.render()does not modify the container node (only modifies the children of the container). In the future, it may be possible to insert a component to an existing DOM node without overwriting the existing children.
ReactDOM.render()currently returns a reference to the root
ReactComponentinstance. However, using this return value is legacy and should be avoided because future versions of React may render components asynchronously in some cases. If you need a reference to the root
ReactComponentinstance, the preferred solution is to attach a callback ref to the root element.
boolean unmountComponentAtNode(DOMElement container)
Remove a mounted React component from the DOM and clean up its event handlers and state. If no component was mounted in the container, calling this function does nothing. Returns
true if a component was unmounted and
false if there was no component to unmount.
DOMElement findDOMNode(ReactComponent component)
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. In most cases, you can attach a ref to the DOM node and avoid using
findDOMNode at all. When
findDOMNode()is an escape hatch used to access the underlying DOM node. In most cases, use of this escape hatch is discouraged because it pierces the component abstraction.
findDOMNode()only works on mounted components (that is, components that have been placed in the DOM). If you try to call this on a component that has not been mounted yet (like calling
render()on a component that has yet to be created) an exception will be thrown.
findDOMNode()cannot be used on stateless components.
react-dom/server package allows you to render your components on the server.
string renderToString(ReactElement element)
Render a ReactElement to its initial HTML. This should only be used on the server. React will return an HTML string. You can use this method to generate HTML on the server and send the markup down on the initial request for faster page loads and to allow search engines to crawl your pages for SEO purposes.
If you call
ReactDOM.render() 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.
string renderToStaticMarkup(ReactElement element)
renderToString, except this doesn't create extra DOM attributes such as
data-react-id, that React uses internally. This is useful if you want to use React as a simple static page generator, as stripping away the extra attributes can save lots of bytes.