Using performance.now():

var t0 = performance.now()

doSomething()   // <---- The function you're measuring time for 

var t1 = performance.now()
console.log("Call to doSomething took " + (t1 - t0) + " milliseconds.")

NodeJs : it is required to import the performance class


Using console.time : ~~(non-standard)~~ (living standard)

console.time('someFunction')

someFunction() // Whatever is timed goes between the two "console.time"

console.timeEnd('someFunction')

Note :