how to time things in javascript code example

Example 1: timer in javascript

//single event i.e. alarm, time in milliseconds
var timeout = setTimeout(function(){yourFunction()},10000);
//repeated events, gap in milliseconds
var interval = setInterval(function(){yourFunction()},1000);

Example 2: javascipt delay

function sleep(ms) {
  return new Promise(resolve => setTimeout(resolve, ms));
}

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