react-lifecycle-cheatsheet.md

Lifecycle (in order)	Triggered When	Use When
getDefaultProps	Triggered when	Useful when
The result of getDefaultProps() will be cached and used to ensure that this.props.value will have a value if it was not specified by the parent component.
componentWillMount()	Triggered before render().	Useful when
componentDidMount()	Triggered Called after render. Can access refs. The componentDidMount() method of child components is invoked before that of parent components. This is the place to call external libraries, use setTimeout, make ajax requests	Useful when
shouldComponentUpdate(nextProps, nextState)	Triggered when updates	Useful when called when there are new props or state changes. return false to prevent a render. good for performance.
componentWillReceiveProps(nextProps)	Triggered when view is updated	Useful when Called before render when props change. Access to old props. It is not triggered after the component is mounted.
componentWillUpdate(nextProps, nextState)	Triggered when immediately before rendering when new props or state are being received. Not called for the initial render. Cannot use setState in this method. Use componentWillReceiveProps instead. Use this as an opportunity to perform preparation before an update occurs.	Useful when
render	Triggered when the state changes.	Useful when
componentDidUpdate(prevState, prevProps)	Triggered when updates	Useful when you want to access to prevState, prevProps Use this as an opportunity to operate on the DOM when the component has been updated.
componentWillUnmount	Triggered when	Useful to clean up event bindings, etc.

Lifecycle (in order)	Triggered When	Use When
getDefaultProps	Triggered when	Useful when
The result of getDefaultProps() will be cached and used to ensure that this.props.value will have a value if it was not specified by the parent component.
componentWillMount()	Triggered before render().	Useful when
componentDidMount()	Triggered Called after render. Can access refs. The componentDidMount() method of child components is invoked before that of parent components. This is the place to call external libraries, use setTimeout, make ajax requests	Useful when
shouldComponentUpdate(nextProps, nextState)	Triggered when updates	Useful when called when there are new props or state changes. return false to prevent a render. good for performance.
componentWillReceiveProps(nextProps)	Triggered when view is updated	Useful when Called before render when props change. Access to old props. It is not triggered after the component is mounted.
componentWillUpdate(nextProps, nextState)	Triggered when immediately before rendering when new props or state are being received. Not called for the initial render. Cannot use setState in this method. Use componentWillReceiveProps instead. Use this as an opportunity to perform preparation before an update occurs.	Useful when
render	Triggered when the state changes.	Useful when
componentDidUpdate(prevState, prevProps)	Triggered when updates	Useful when you want to access to prevState, prevProps Use this as an opportunity to operate on the DOM when the component has been updated.
componentWillUnmount	Triggered when	Useful to clean up event bindings, etc.

React lifecycle cheatsheet

Method (in order)	Side effects1	State updates2	Example uses
Mounting
componentWillMount		✓	Constructor equivalent for createClass
render			Create and return element(s)
componentDidMount	✓	✓	DOM manipulations, network requests, etc.
Updating
componentWillReceiveProps		✓	Update state based on changed props
shouldComponentUpdate			Compare inputs and determine if render needed
componentWillUpdate			Set/reset things (eg cached values) before next render
render			Create and return element(s)
componentDidUpdate	✓	✓	DOM manipulations, network requests, etc.
Unmounting
componentWillUnmount	✓		DOM manipulations, network requests, etc.

For more information see here.

1. "Side effects" refer to modifying variables outside of the instance, async operations, etc.
2. "State updates" refer to the current instance only (eg this.setState).