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What are the React lifecycle methods? in REACT
Practice
React 16.3+
getDerivedStateFromProps: Called immediately before
render()
and invoked on every render. It exists for the rare use cases where you need derived state. It is worth reading if you need derived state .
componentDidMount: runs after the first render, and this is where all AJAX requests, DOM or state updates should happen, and where event listeners should be set up.
shouldComponentUpdate: Determines whether the component will update or not. By default it returns
true
. If you are sure the component should not re-render after a state or props update, you can return a false value. This is a great place to improve performance, since it lets you prevent a re-render when the component receives a new prop.
getSnapshotBeforeUpdate: Runs immediately before the rendered output is committed to the DOM. Any value returned from it will be passed to
componentDidUpdate()
. This is useful for capturing information from the DOM, i.e. the scroll position.
componentDidUpdate: it is mainly used to update the DOM in response to prop or state changes. It will not fire if
shouldComponentUpdate()
returns
false
.
componentWillUnmount It will be used to cancel any outgoing network requests or to remove all event listeners associated with the component.
Before 16.3
componentWillMount: runs before rendering and is used for application-level configuration in the root component.
componentDidMount: runs after the first render, and this is where all AJAX requests, DOM or state updates should happen, and where event listeners should be set up.
componentWillReceiveProps: Runs when a particular prop is updated in order to trigger state transitions.
shouldComponentUpdate: Determines whether the component will update or not. By default it returns
true
. If you are sure the component should not re-render after a state or props update, you can return a false value. This is a great place to improve performance, since it lets you prevent a re-render when the component receives a new prop.
componentWillUpdate: Runs before the component is re-rendered, when there are props and state changes confirmed by
shouldComponentUpdate()
which returns true.
componentDidUpdate: it is mainly used to update the DOM in response to prop or state changes.
componentWillUnmount: will be used to cancel any outgoing network requests or to remove all event listeners associated with the component.
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