react.dev/docs/ref-01-top-level-api.md

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top-level-api	Top-Level API	top-level-api.html	component-api.html	/docs/reference.html

React

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 require() it.

React.Component

class Component

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.

React.createClass

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.

React.createElement

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 React.createClass).

React.cloneElement

ReactElement cloneElement(
  ReactElement element,
  [object props],
  [children ...]
)

Clone and return a new ReactElement using 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 React.addons.cloneWithProps, key and 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.

React.createFactory

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 ReactClass.

React.render

ReactComponent render(
  ReactElement element,
  DOMElement container,
  [function callback]
)

Render a ReactElement into the DOM in the supplied container and return a reference to the component.

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.

Note:

React.render() replaces the contents of the container node you pass in. In the future, it may be possible to insert a component to an existing DOM node without overwriting the existing children.

React.unmountComponentAtNode

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.

React.renderToString

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 React.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.

React.renderToStaticMarkup

string renderToStaticMarkup(ReactElement element)

Similar to 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.

React.isValidElement

boolean isValidElement(* object)

Verifies the object is a ReactElement.

React.findDOMNode

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. When render returns null or false, findDOMNode returns null.

React.DOM

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

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

React.Children provides utilities for dealing with the this.props.children opaque data structure.

React.Children.map

object React.Children.map(object children, function fn [, object thisArg])

Invoke fn on every immediate child contained within children with this set to thisArg. If children is a nested object or array it will be traversed: fn will never be passed the container objects. If children is null or undefined returns null or undefined rather than an empty object.

React.Children.forEach

React.Children.forEach(object children, function fn [, object thisArg])

Like React.Children.map() but does not return an object.

React.Children.count

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 map or forEach would be invoked.

React.Children.only

object React.Children.only(object children)

Return the only child in children. Throws otherwise.