How can I convert 'HH:MM:SS ' format to seconds in JavaScript

We are required to write a function that takes in a ‘HH:MM:SS’ string and returns the number of seconds. For example −

countSeconds(‘12:00:00’) //43200
countSeconds(‘00:30:10’) //1810

Let’s write the code for this. We will split the string, convert the array of strings into an array of numbers and return the appropriate number of seconds.

The full code for this will be −

Example

const timeString = '23:54:43';
const other = '12:30:00';
const withoutSeconds = '10:30';
const countSeconds = (str) => {
   const [hh = '0', mm = '0', ss = '0'] = (str || '0:0:0').split(':');
   const hour = parseInt(hh, 10) || 0;
   const minute = parseInt(mm, 10) || 0;
   const second = parseInt(ss, 10) || 0;
   return (hour*3600) + (minute*60) + (second);
};
console.log(countSeconds(timeString));
console.log(countSeconds(other));
console.log(countSeconds(withoutSeconds));

Output

The output in the console will be −

86083
45000
37800