Class Component<P, S, SS>

Type Parameters

P = {}
S = {}
SS = any

Hierarchy (View Summary)

ComponentLifecycle<P, S, SS>
- Component

Constructors

constructor

new Component(props: P): Component<P, S, SS>
Type Parameters
- P = {}
- S = {}
- SS = any
Parameters
- props: P
Returns Component<P, S, SS>
Inherited from ComponentLifecycle<P, S, SS>.constructor
- Defined in node_modules/@types/react/index.d.ts:944

Properties

context

context: unknown

If using the new style context, re-declare this in your class to be the React.ContextType of your static contextType. Should be used with type annotation or static contextType.

Example

static contextType = MyContext
// For TS pre-3.7:
context!: React.ContextType<typeof MyContext>
// For TS 3.7 and above:
declare context: React.ContextType<typeof MyContext>

`Static` `Optional`contextType

contextType?: Context<any>

If set, this.context will be set at runtime to the current value of the given Context.

Example

type MyContext = number
const Ctx = React.createContext<MyContext>(0)

class Foo extends React.Component {
  static contextType = Ctx
  context!: React.ContextType<typeof Ctx>
  render () {
    return <>My context's value: {this.context}</>;
  }
}

See

https://react.dev/reference/react/Component#static-contexttype

`Static` `Optional`propTypes

propTypes?: any

Ignored by React.

Deprecated

Only kept in types for backwards compatibility. Will be removed in a future major release.

Methods

`Optional`componentDidCatch

componentDidCatch(error: Error, errorInfo: ErrorInfo): void
Catches exceptions generated in descendant components. Unhandled exceptions will cause the entire component tree to unmount.
Parameters
- error: Error
- errorInfo: ErrorInfo
Returns void
Inherited from ComponentLifecycle.componentDidCatch
- Defined in node_modules/@types/react/index.d.ts:1190

`Optional`componentDidMount

componentDidMount(): void
Called immediately after a component is mounted. Setting state here will trigger re-rendering.

Returns void
Inherited from ComponentLifecycle.componentDidMount
- Defined in node_modules/@types/react/index.d.ts:1169

`Optional`componentDidUpdate

componentDidUpdate(
 prevProps: Readonly,
 prevState: Readonly<S>,
 snapshot?: SS,
): void
Called immediately after updating occurs. Not called for the initial render.

The snapshot is only present if getSnapshotBeforeUpdate is present and returns non-null.
Parameters
- prevProps: Readonly
- prevState: Readonly<S>
- Optionalsnapshot: SS
Returns void
Inherited from ComponentLifecycle.componentDidUpdate
- Defined in node_modules/@types/react/index.d.ts:1232

`Optional`componentWillMount

componentWillMount(): void
Called immediately before mounting occurs, and before Component.render. Avoid introducing any side-effects or subscriptions in this method.

Note: the presence of getSnapshotBeforeUpdate or StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps prevents this from being invoked.

Returns void
Deprecated
16.3, use componentDidMount or the constructor instead; will stop working in React 17
See
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#initializing-state
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#gradual-migration-path
Inherited from ComponentLifecycle.componentWillMount
- Defined in node_modules/@types/react/index.d.ts:1248

`Optional`componentWillReceiveProps

componentWillReceiveProps(nextProps: Readonly): void
Called when the component may be receiving new props. React may call this even if props have not changed, so be sure to compare new and existing props if you only want to handle changes.

Calling Component.setState generally does not trigger this method.

Note: the presence of getSnapshotBeforeUpdate or StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps prevents this from being invoked.
Parameters
- nextProps: Readonly
Returns void
Deprecated
16.3, use static StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps instead; will stop working in React 17
See
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#updating-state-based-on-props
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#gradual-migration-path
Inherited from ComponentLifecycle.componentWillReceiveProps
- Defined in node_modules/@types/react/index.d.ts:1279

`Optional`componentWillUnmount

componentWillUnmount(): void
Called immediately before a component is destroyed. Perform any necessary cleanup in this method, such as cancelled network requests, or cleaning up any DOM elements created in componentDidMount.

Returns void
Inherited from ComponentLifecycle.componentWillUnmount
- Defined in node_modules/@types/react/index.d.ts:1185

`Optional`componentWillUpdate

componentWillUpdate(nextProps: Readonly, nextState: Readonly<S>): void
Called immediately before rendering when new props or state is received. Not called for the initial render.

Note: You cannot call Component.setState here.

Note: the presence of getSnapshotBeforeUpdate or StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps prevents this from being invoked.
Parameters
- nextProps: Readonly
- nextState: Readonly<S>
Returns void
Deprecated
16.3, use getSnapshotBeforeUpdate instead; will stop working in React 17
See
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#reading-dom-properties-before-an-update
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#gradual-migration-path
Inherited from ComponentLifecycle.componentWillUpdate
- Defined in node_modules/@types/react/index.d.ts:1311

forceUpdate

forceUpdate(callback?: () => void): void
Parameters
- Optionalcallback: () => void
Returns void
- Defined in node_modules/@types/react/index.d.ts:954

`Optional`getSnapshotBeforeUpdate

getSnapshotBeforeUpdate(
prevProps: Readonly,
prevState: Readonly<S>,
): null | SS
Runs before React applies the result of render to the document, and returns an object to be given to componentDidUpdate. Useful for saving things such as scroll position before render causes changes to it.

Note: the presence of this method prevents any of the deprecated lifecycle events from running.
Parameters
- prevProps: Readonly
- prevState: Readonly<S>
Returns null | SS
Inherited from ComponentLifecycle.getSnapshotBeforeUpdate
- Defined in node_modules/@types/react/index.d.ts:1226

render

render(): ReactNode
Returns ReactNode
- Defined in node_modules/@types/react/index.d.ts:955

setState

setState<K extends string | number | symbol>(
 state:
 | null
 | S
 | (prevState: Readonly<S>, props: Readonly) => null | S | Pick<S, K>
 | Pick<S, K>,
 callback?: () => void,
): void
Type Parameters
- K extends string | number | symbol
Parameters
- state:
 | null
 | S
 | (prevState: Readonly<S>, props: Readonly) => null | S | Pick<S, K>
 | Pick<S, K>
- Optionalcallback: () => void
Returns void
- Defined in node_modules/@types/react/index.d.ts:949

`Optional`shouldComponentUpdate

shouldComponentUpdate(nextProps: Readonly, nextState: Readonly<S>): boolean
Called to determine whether the change in props and state should trigger a re-render.

Component always returns true. PureComponent implements a shallow comparison on props and state and returns true if any props or states have changed.

If false is returned, Component.render, componentWillUpdate and componentDidUpdate will not be called.
Parameters
- nextProps: Readonly
- nextState: Readonly<S>
Returns boolean
Inherited from ComponentLifecycle.shouldComponentUpdate
- Defined in node_modules/@types/react/index.d.ts:1180

`Optional`UNSAFE_componentWillMount

UNSAFE_componentWillMount(): void
Called immediately before mounting occurs, and before Component.render. Avoid introducing any side-effects or subscriptions in this method.

This method will not stop working in React 17.

Note: the presence of getSnapshotBeforeUpdate or StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps prevents this from being invoked.

Returns void
Deprecated
16.3, use componentDidMount or the constructor instead
See
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#initializing-state
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#gradual-migration-path
Inherited from ComponentLifecycle.UNSAFE_componentWillMount
- Defined in node_modules/@types/react/index.d.ts:1263

`Optional`UNSAFE_componentWillReceiveProps

UNSAFE_componentWillReceiveProps(nextProps: Readonly): void
Called when the component may be receiving new props. React may call this even if props have not changed, so be sure to compare new and existing props if you only want to handle changes.

Calling Component.setState generally does not trigger this method.

This method will not stop working in React 17.

Note: the presence of getSnapshotBeforeUpdate or StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps prevents this from being invoked.
Parameters
- nextProps: Readonly
Returns void
Deprecated
16.3, use static StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps instead
See
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#updating-state-based-on-props
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#gradual-migration-path
Inherited from ComponentLifecycle.UNSAFE_componentWillReceiveProps
- Defined in node_modules/@types/react/index.d.ts:1297

`Optional`UNSAFE_componentWillUpdate

UNSAFE_componentWillUpdate(nextProps: Readonly, nextState: Readonly<S>): void
Called immediately before rendering when new props or state is received. Not called for the initial render.

Note: You cannot call Component.setState here.

This method will not stop working in React 17.

Note: the presence of getSnapshotBeforeUpdate or StaticLifecycle.getDerivedStateFromProps getDerivedStateFromProps prevents this from being invoked.
Parameters
- nextProps: Readonly
- nextState: Readonly<S>
Returns void
Deprecated
16.3, use getSnapshotBeforeUpdate instead
See
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#reading-dom-properties-before-an-update
- https://legacy.reactjs.org/blog/2018/03/27/update-on-async-rendering.html#gradual-migration-path
Inherited from ComponentLifecycle.UNSAFE_componentWillUpdate
- Defined in node_modules/@types/react/index.d.ts:1327

Class Component<P, S, SS>

Type Parameters

Hierarchy (View Summary)

Index

Constructors

Properties

Methods

Constructors

constructor

Type Parameters

Parameters

Returns Component<P, S, SS>

Properties

context

Example

See

Readonlyprops

state

Static OptionalcontextType

Example

See

Static OptionalpropTypes

Deprecated

Methods

OptionalcomponentDidCatch

Parameters

Returns void

OptionalcomponentDidMount

Returns void

OptionalcomponentDidUpdate

Parameters

Returns void

OptionalcomponentWillMount

Returns void

Deprecated

See

OptionalcomponentWillReceiveProps

Parameters

Returns void

Deprecated

See

OptionalcomponentWillUnmount

Returns void

OptionalcomponentWillUpdate

Parameters

Returns void

Deprecated

See

forceUpdate

Parameters

Returns void

OptionalgetSnapshotBeforeUpdate

Parameters

Returns null | SS

render

Returns ReactNode

setState

Type Parameters

Parameters

Returns void

OptionalshouldComponentUpdate

Parameters

Returns boolean

OptionalUNSAFE_componentWillMount

Returns void

Deprecated

See

OptionalUNSAFE_componentWillReceiveProps

Parameters

Returns void

Deprecated

See

OptionalUNSAFE_componentWillUpdate

Parameters

Returns void

Deprecated

See

Settings

On This Page

`Readonly`props

`Static` `Optional`contextType

`Static` `Optional`propTypes

`Optional`componentDidCatch

`Optional`componentDidMount

`Optional`componentDidUpdate

`Optional`componentWillMount

`Optional`componentWillReceiveProps

`Optional`componentWillUnmount

`Optional`componentWillUpdate

`Optional`getSnapshotBeforeUpdate

`Optional`shouldComponentUpdate

`Optional`UNSAFE_componentWillMount

`Optional`UNSAFE_componentWillReceiveProps

`Optional`UNSAFE_componentWillUpdate