To measure the time taken by a function to execute in JavaScript, use the “performance.now()” or “console.time()” method.
Method 1: Using “performance.now()” function
You can use the performance.now() method to measure a function’s time to execute with higher precision.
Syntax
start = performance.now();
function_to_call();
end = performance.now();
Example
function mainFunc() {
const t0 = performance.now();
// code to be measured goes here
const t1 = performance.now();
console.log(`myFunction took ${t1 - t0} milliseconds.`);
}
mainFunc();
Output
myFunction took 0.030916988849639893 milliseconds.
In this code, the performance.now() method is used to get high-precision timestamps before and after the code to be measured is executed.
The difference between the two timestamps is then logged to the console to output the time taken in milliseconds.
Method 2: Using the console.time() method
To measure the time a function takes to execute in JavaScript, use the “performance.now()” or “console.time()” method.
Syntax
console.time('label');
function_to_call();
console.timeEnd('label');
Example
function mainFunc() {
console.time('mainFunc');
// code to be measured goes here
console.timeEnd('mainFunc');
}
mainFunc();
Output
mainFunc: 0.03ms
In this code, the console.time() method is called with a label of ‘mainFunc’ to start the timer. The code to be measured is then executed, and the console.timeEnd() method is called with the same label to stop the timer and output the time taken in milliseconds to the console.
The label passed to console.time() and console.timeEnd() should match; otherwise, you will encounter unexpected results.

Krunal Lathiya is a seasoned Computer Science expert with over eight years in the tech industry. He boasts deep knowledge in Data Science and Machine Learning. Versed in Python, JavaScript, PHP, R, and Golang. Skilled in frameworks like Angular and React and platforms such as Node.js. His expertise spans both front-end and back-end development. His proficiency in the Python language stands as a testament to his versatility and commitment to the craft.