CallBack way to measure execution time in Node.js

CallBackWayToMeasureExecutionTime.js

var sleepFunction = function(milliSecondsToSleep) {
    let startTime = new Date().getTime();
    setTimeout(function() {
        let endTime = new Date().getTime();
        console.log("My job done in " + (endTime - startTime) + " ms");
    }, milliSecondsToSleep);
}

let startTime = new Date().getTime();
sleepFunction(1000);
sleepFunction(1000);
let endTime = new Date().getTime();
console.log("Program took " + (endTime - startTime) + " ms to complete");