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);

 let myVar = setInterval(myTimer, 1000);

 
function myTimer() {
  let d = new Date();
  document.getElementById("demo").innerHTML = d.toLocaleTimeString();

} 

//to repeat a function here, MyTimer at every 1000 ms ie 1 sec use this
 var myVar = setInterval(myTimer, 1000);
//replace myTimer with your function, and 1000 with the no of seconds between each function call
// used it run refresh function to refresh a page at 300000ms ie every 5 minutes
//var myVar = setInterval(refreshPage, 300000);
function myTimer() {
  var d = new Date();
  document.getElementById("demo").innerHTML = d.toLocaleTimeString();

}