How to measure execution time of javascript function

In this post, I will show you how to measure the execution time of any function in Javascript.
Javascript console API has two functions console.time and console.timeEnd

  • console.time - start the timer
  • console.timeEnd - Stops a timer that was previously started by calling console.time() and prints the result to stdout:

for example, let’s suppose you have the following javascript function, which calculates the factorial of a given number

const fact = (number) => {
    if (number < 1) {
        return 1;
    else {
        return number * fact(number - 1);

and you want to calculate the execution time of the function.
You can wrap this function between console.time and console.timeEnd which will display the execution time on stdout


if you execute the above script, you will see the following output

Factorial: 0.175ms

This approach is not reusable. You can create one helper function as below

const measure = (label, fn) => {

and use like below

measure('Factorial', () => {    

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