Javascript Event Loop
const first = () => console.log('Hi,i am first');
const second = () => console.log('Hi,i am second');
const third = () => console.log('Hi,i am third');
const fourth = () => {
    first();
    setTimeout(second, 4000);
    //store in queue & it will execute after 4 seconds
    setTimeout(third, 2000);
    //store in queue & it will execute after 2 seconds
    console.log('Hi,i am fourth');
};
fourth();
//Expected output:
/*Hi,i am first
  Hi,i am fourth
  Hi,i am third
  Hi,i am second 
*/