react componentwillupdate code example

Example 1: lifecycle method react

INITIALIZATION= setup props and state 
MOUNTING= constructor->componentWillMount->render->componentDidMount//Birth
UPDATE= shouldComponentUpdate->componentWillUpdate->render
  		->componentDidUpdate //Growth
UNMOUNTING= componentWillUnmount //Death

Example 2: componentwillreceiveprops hooks

SomeComponent (props) => {

    useEffect( () => {
        console.log('someProp updated');
    }, [props.someProp])


    return <div>Hi {props.someProp}</div>
}

Example 3: component did mmount

componentDidMount()

Example 4: component did mmount

componentDidUpdate(prevProps, prevState, snapshot)

Example 5: componentwillreceiveprops hooks

const { useState, useEffect, useMemo } = React;

function App() {
  const [count, setCount] = useState(50);

  useEffect(() => {
    setTimeout(() => {
      setCount(150);
    }, 2000);
  }, []);

  return <DisplayCount count={count} />;
}

function DisplayCount(props) {
  const count = useMemo(() => props.count > 100 ? 100 : props.count, [props.count]);

  return <div> {count} </div>;
}

ReactDOM.render(<App />, document.getElementById("root"));