Learn React with TypeScript 3

getDerivedStateFromProps

getDerivedStateFromProps is invoked every time a component is rendered. It can be used to change state when certain props change. This is a static method in a component class that returns the changed state, or null if there are no changes to the state.

Let's have a look at this life cycle method in our app. Add the following at the top of the App class:

public static getDerivedStateFromProps(props: {}, state: IState) {  console.log("getDerivedStateFromProps", props, state);  return null;}

If we look in the console when the app is running, we see that our method is called each time the countdown decrements: