Converting HH:MM:SS format to seconds in JavaScript

In this tutorial, we are going to learn about how to convert the "hh:mm:ss" string format to seconds in JavaScript.

Consider, we have a following time string:

const timeString = "08:35:42";

Now, we need to convert the above format into seconds.

To convert a hh:mm:ss format to seconds, first we need to split the string by colon : and multiply the hour value with 3600 and minutes value with 60 then we need to add everything to get the seconds.

Here is an example:

const timeString = "08:35:42"; // input string

const arr = timeString.split(":"); // splitting the string by colon

const seconds = arr[0]*3600+arr[1]*60+(+arr[2]); // converting

console.log(seconds);

Output:

30942

Note: In the above code we are multiplying hours with 3600 and minutes with 60 because 1 hour contains 3600 seconds, 1 minute contains 60 seconds.

We can also create our own reusable function like this to convert hh:mm:ss to seconds.

function convertHMS(timeString){

  const arr = timeString.split(":");
  const seconds = arr[0]*3600+arr[1]*60+(+arr[2]);
  return seconds;

}

console.log(convertHMS("08:35:42")); // 30942