Converting a timespan of HH:MM:SS to MS using Javascript

msConverter.js

console.log('qa', (1 * 60 * 60 * 1000) + (40 * 60 * 1000) + (30 * 1000))



const rawTimespan = '01:40:30';
const rawTimespanArray = rawTimespan.split(':').slice(-3);


const timespanFromReduce = rawTimespanArray.reduce((timespan, segment, i, rawTimespanArray) => {

	if (rawTimespanArray.length - 1 === i) {
		// we are processing the last one (ms), so multiply by 1000
		return (parseFloat(segment) + timespan) * 1000;
	} else {
		return (parseFloat(segment) + timespan) * 60;
	}

}, 0);

console.log('timespanFromReduce', timespanFromReduce);


let timespanFromWhile = 0;

while(rawTimespanArray.length > 0) {
	const timechunk = parseFloat(rawTimespanArray.shift());
	
	if (rawTimespanArray.length === 0) {
		timespanFromWhile = (timechunk + timespanFromWhile) * 1000;
	} else {
		timespanFromWhile = (timechunk + timespanFromWhile) * 60;
	}
}

console.log('timespanFromWhile', timespanFromWhile);