javascript - How to measure time taken by a function to execute

I need to get execution time in milliseconds.

I originally asked this question back in 2008. The accepted answer

then was to use new Date().getTime() However, we can all agree now
that using the standard performance.now() API is more
appropriate. I am therefore changing the accepted answer to this one.

Answer

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

---

console.time('someFunction');

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

console.timeEnd('someFunction');

Note:
The string being pass to the time() and timeEnd() methods must match
(for the timer to finish as expected).

console.time() documentations:

1. NodeJS documentation regarding


2. MDN (client-side) documentation