Sleep Function In JavaScript | Async/Sync

Asynchronous Sleep

      /**
* Delay for a number of milliseconds
*/
function sleep(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

console.log('Hello');
sleep(2000)
.then(() => { 
     console.log('World!'); 
});
    

Synchronous Sleep

      /**
* Delay for a number of milliseconds
*/
function sleep(delay) {
    var start = new Date().getTime();
    while (new Date().getTime() < start + delay);
}

console.log('Hello');
sleep(2000);
console.log('World');