how to use componentdidmount in functional component

1// passing an empty array as second argument triggers the callback in useEffect
2// only after the initial render thus replicating `componentDidMount` lifecycle behaviour
3useEffect(() => {
4  if(!props.fetched) {
5 	 props.fetchRules();
6  }
7  console.log('mount it!');
8}, []);
9
10// componentDidUpdate
11useEffect({
12	your code here
13}) 
14
15// For componentDidUpdate
16useEffect(() => {
17  // Your code here
18}, [yourDependency]);
19
20// For componentWillUnmount
21useEffect(() => {
22  // componentWillUnmount
23  return () => {
24     // Your code here
25  }
26}, [yourDependency]);
27

1useEffect(() => {
2  window.addEventListener('mousemove', () => {});
3
4  // returned function will be called on component unmount 
5  return () => {
6    window.removeEventListener('mousemove', () => {})
7  }
8}, [])