componentWillUnmount method

@mustCallSuper @override void componentWillUnmount()

ReactJS lifecycle method that is invoked immediately before a Component is unmounted from the DOM.

Perform any necessary cleanup in this method, such as invalidating timers or cleaning up any DOM Elements that were created in componentDidMount.

See: reactjs.org/docs/react-component.html#componentwillunmount

Implementation

@mustCallSuper
@override
void componentWillUnmount() {
  super.componentWillUnmount();
  _isUnmounted = true;
  _cancelTransitionEndTimer();
  _cancelTransitionEventListener();
}