JavaScript performance.now() Method

In JavaScript performance.now() method can be used to check the performance of your code. You can check the execution time of your code using this method.

Syntax:

let t = performance.now();

Parameter: It does not take any parameter

Return value: It returns value of time in milliseconds. It is the time elapsed since execution started 

The code below will give you a brief idea of how this code performs.

Example 1:

<script>
  const t0 = performance.now();
  for (let i = 0; i < 10; i++) {
    console.log(i);
  }
  const t1 = performance.now();
  console.log(`Call to doSomething took ${t1 - t0} milliseconds.`);
</script>

Output: In the above code, variables t0 and t1 are used to store starting time and ending time respectively, and while printing we subtracted t0 from t1 to print the time required in the execution of the code.

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"Call to doSomething took 1.7899998929351568 milliseconds."

Example 2:

<script>
  const t0 = performance.now();
  for (let i = 0; i < 5; i++) {
    console.log(i);
  }
  const t1 = performance.now();
  console.log(`Call to doSomething took ${t1 - t0} milliseconds.`);
</script>

Output:

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"Call to doSomething took 0.7100000511854887 milliseconds."

Supported Browsers: The browsers supported by JavaScript performance.now() method are listed below:

• Google Chrome
• Internet Explorer
• Mozilla Firefox
• Opera
• Safari

We have a Cheat Sheet on Javascript where we covered all the important topics of Javascript to check those please go through Javascript Cheat Sheet-A Basic guide to JavaScript.