LifeCycleComponent Class — react Architecture

Source Code

packages/react-dom/src/__tests__/ReactComponentLifeCycle-test.js lines 274–314

    class LifeCycleComponent extends React.Component {
      constructor(props, context) {
        super(props, context);
        this._testJournal = {};
        const initState = {
          hasWillMountCompleted: false,
          hasDidMountCompleted: false,
          hasRenderCompleted: false,
          hasWillUnmountCompleted: false,
        };
        this._testJournal.returnedFromGetInitialState = clone(initState);
        this.state = initState;
      }

      UNSAFE_componentWillMount() {
        this._testJournal.stateAtStartOfWillMount = clone(this.state);
        this.state.hasWillMountCompleted = true;
      }

      componentDidMount() {
        this._testJournal.stateAtStartOfDidMount = clone(this.state);
        this.setState({hasDidMountCompleted: true});
      }

      render() {
        const isInitialRender = !this.state.hasRenderCompleted;
        if (isInitialRender) {
          this._testJournal.stateInInitialRender = clone(this.state);
        } else {
          this._testJournal.stateInLaterRender = clone(this.state);
        }
        // you would *NEVER* do anything like this in real code!
        this.state.hasRenderCompleted = true;
        return <div ref={React.createRef()}>I am the inner DIV</div>;
      }

      componentWillUnmount() {
        this._testJournal.stateAtStartOfWillUnmount = clone(this.state);
        this.state.hasWillUnmountCompleted = true;
      }
    }