Parse Youtube v3 API Duration to seconds with Javascript

youtubeDurationToSeconds

function youtubeDurationToSeconds(duration) {
	var hours   = 0;
	var minutes = 0;
	var seconds = 0;

	// Remove PT from string ref: https://developers.google.com/youtube/v3/docs/videos#contentDetails.duration
	duration = duration.replace('PT','');

	// If the string contains hours parse it and remove it from our duration string
	if (duration.indexOf('H') > -1) {
		hours_split = duration.split('H');
		hours       = parseInt(hours_split[0]);
		duration    = hours_split[1];
	}

	// If the string contains minutes parse it and remove it from our duration string
	if (duration.indexOf('M') > -1) {
		minutes_split = duration.split('M');
		minutes       = parseInt(minutes_split[0]);
		duration      = minutes_split[1];
	}

	// If the string contains seconds parse it and remove it from our duration string
	if (duration.indexOf('S') > -1) {
		seconds_split = duration.split('S');
		seconds       = parseInt(seconds_split[0]);
	}

	// Math the values to return seconds
	return (hours * 60 * 60) + (minutes * 60) + seconds;
}

10/05/2021 EDIT: Found a bug, so added some extra bits

Amazing thank you. I made some filthy modifications that could look better, but give you back the string as H:M:S.

Return block is this:

        var str = "";
        
        if (hours != 0) { str += hours + ":"; }

        if (minutes == 0) { str += "00" + ":"; }
        else if (minutes < 10) { str += "0" + minutes + ":"; }
        else if (minutes > 10) { str += minutes + ":"; }
        else if (minutes == 0) { str += "00:" }

        if (seconds > 0 && seconds < 10) { str += "0" + seconds; }
        else if (seconds < 10) { str += "0" + seconds; }
        else if (seconds > 10) { str += seconds; }
        else if (seconds == 0) { str += "00" }

        return str;

Nice addition @daveshirman