how to check time taken to run code js code example

Example 1: time taken for a function javascript

console.time("timer");   //start time with name = timer
console.timeEnd("timer"); //end timer and log time difference

Example 2: javascript count time

// The getTime() method returns the number of milliseconds since midnight of January 1, 1970.


var start = new Date().getTime();

for (i = 0; i < 50000; ++i) {
// do something
}

var end = new Date().getTime();
var time = end - start;
alert('Execution time: ' + time);