react useefeect code example

Example 1: react useeffect

import React, { useEffect } from 'react';
	
	const [data,setData]=useState()
    useEffect(() => {
        fetch(`put your url/api request in here`)
        .then(res=>res.json())
        .then(json => setData(json))
    },[])

Example 2: clean up useeffect

useEffect(() => {
    function handleStatusChange(status) {
      setIsOnline(status.isOnline);
    }
    ChatAPI.subscribeToFriendStatus(props.friend.id, handleStatusChange);
    // Specify how to clean up after this effect:
    return () => {
      ChatAPI.unsubscribeFromFriendStatus(props.friend.id, handleStatusChange);
    };
  });