This order should make more sense; it moves important functions like React.renderComponent up and deprecated/discouraged ones like transferPropsTo and setProps down. No content changes.
`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.Children
`React.Children` provides utilities for dealing with the `this.props.children` opaque data structure.
#### React.Children.map
```javascript
object React.Children.map(object children, function fn [, object context])
```
Invoke `fn` on every immediate child contained within `children` with `this` set to `context`. 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
```javascript
React.Children.forEach(object children, function fn [, object context])
```
Like `React.Children.map()` but does not return an object.
#### React.Children.only
```javascript
object React.Children.only(object children)
```
Return the only child in `children`. Throws otherwise.
### 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.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/docs/reusable-components.html).
### React.initializeTouchEvents
```javascript
initializeTouchEvents(boolean shouldUseTouch)
```
Configure React's event system to handle touch events on mobile devices.
Similar to `renderComponentToString`, 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.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.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/docs/reusable-components.html).
### React.initializeTouchEvents
```javascript
initializeTouchEvents(boolean shouldUseTouch)
```
Configure React's event system to handle touch events on mobile devices.
### React.Children
`React.Children` provides utilities for dealing with the `this.props.children` opaque data structure.
#### React.Children.map
```javascript
object React.Children.map(object children, function fn [, object context])
```
Invoke `fn` on every immediate child contained within `children` with `this` set to `context`. 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
```javascript
React.Children.forEach(object children, function fn [, object context])
```
Like `React.Children.map()` but does not return an object.
#### React.Children.only
```javascript
object React.Children.only(object children)
```
Return the only child in `children`. Throws otherwise.
Component classes created by `React.createClass()` return instances of `ReactComponent` when called. Most of the time when you're using React you're either creating or consuming these component objects.
### getDOMNode
### setState
```javascript
DOMElement getDOMNode()
setState(object nextState[, function callback])
```
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`, `this.getDOMNode()` returns `null`.
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 and the component is re-rendered.
> Notes:
>
> *NEVER* mutate `this.state` directly, as calling `setState()` afterwards may replace the mutation you made. Treat `this.state` as if it were immutable.
>
> `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.
>
> There is no guarantee of synchronous operation of calls to `setState` and calls may be batched for performance gains.
### setProps
### replaceState
```javascript
setProps(object nextProps[, function callback])
replaceState(object nextState[, function callback])
```
When you're integrating with an external JavaScript application you may want to signal a change to a React component rendered with `React.renderComponent()`.
Like `setState()` but deletes any pre-existing state keys that are not in nextState.
Though calling `React.renderComponent()` again on the same node is the preferred way to update a root-level component, you can also call `setProps()` to change its properties and trigger a re-render. In addition, you can supply an optional callback function that is executed once `setProps` is completed and the component is re-rendered.
> Note:
>
> When possible, the declarative approach of calling `React.renderComponent()` again is preferred; it tends to make updates easier to reason about. (There's no significant performance difference between the two approaches.)
>
> This method can only be called on a root-level component. That is, it's only available on the component passed directly to `React.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()`.
### forceUpdate()
```javascript
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()` by calling `forceUpdate()`. You'll also need to call `forceUpdate()` if you mutate `this.state` directly.
### replaceProps
Calling `forceUpdate()` will cause `render()` to be called on the component and its children, but React will still 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.
### getDOMNode
```javascript
replaceProps(object nextProps[, function callback])
DOMElement getDOMNode()
```
Like `setProps()` but deletes any pre-existing props instead of merging the two objects.
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`, `this.getDOMNode()` returns `null`.
### isMounted()
```javascript
bool isMounted()
```
`isMounted()` returns true if the component is rendered into the DOM, false otherwise. You can use this method to guard asynchronous calls to `setState()` or `forceUpdate()`.
### transferPropsTo
@ -74,49 +96,27 @@ Properties that are specified directly on the target component instance (such as
> Use `transferPropsTo` with caution; it encourages tight coupling and makes it easy to accidentally introduce implicit dependencies between components. When in doubt, it's safer to explicitly copy the properties that you need onto the child component.
### setState
### setProps
```javascript
setState(object nextState[, function callback])
setProps(object nextProps[, 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 and the component is re-rendered.
When you're integrating with an external JavaScript application you may want to signal a change to a React component rendered with `React.renderComponent()`.
> Notes:
>
> *NEVER* mutate `this.state` directly, as calling `setState()` afterwards may replace the mutation you made. Treat `this.state` as if it were immutable.
Though calling `React.renderComponent()` again on the same node is the preferred way to update a root-level component, you can also call `setProps()` to change its properties and trigger a re-render. In addition, you can supply an optional callback function that is executed once `setProps` is completed and the component is re-rendered.
> 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.
> When possible, the declarative approach of calling `React.renderComponent()` again is preferred; it tends to make updates easier to reason about. (There's no significant performance difference between the two approaches.)
>
> There is no guarantee of synchronous operation of calls to `setState` and calls may be batched for performance gains.
### replaceState
```javascript
replaceState(object nextState[, function callback])
```
Like `setState()` but deletes any pre-existing state keys that are not in nextState.
### forceUpdate()
```javascript
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()` by calling `forceUpdate()`. You'll also need to call `forceUpdate()` if you mutate `this.state` directly.
Calling `forceUpdate()` will cause `render()` to be called on the component and its children, but React will still 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.
> This method can only be called on a root-level component. That is, it's only available on the component passed directly to `React.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()`.
### isMounted()
### replaceProps
```javascript
bool isMounted()
replaceProps(object nextProps[, function callback])
```
`isMounted()` returns true if the component is rendered into the DOM, false otherwise. You can use this method to guard asynchronous calls to `setState()` or `forceUpdate()`.
Like `setProps()` but deletes any pre-existing props instead of merging the two objects.
Ben Alpert
11 years ago