Converting Youtube Data API V3 video duration format to seconds in JavaScript/Node.js

If you're using moment.js you can simply call...

moment.duration('PT15M33S').asMilliseconds();

= 933000 ms

function YTDurationToSeconds(duration) {
  var match = duration.match(/PT(\d+H)?(\d+M)?(\d+S)?/);

  match = match.slice(1).map(function(x) {
    if (x != null) {
        return x.replace(/\D/, '');
    }
  });

  var hours = (parseInt(match[0]) || 0);
  var minutes = (parseInt(match[1]) || 0);
  var seconds = (parseInt(match[2]) || 0);

  return hours * 3600 + minutes * 60 + seconds;
}

works for these cases:

PT1H
PT23M
PT45S
PT1H23M
PT1H45S
PT23M45S
PT1H23M45S

I suggest this little hack to prevent your problematic case:

function convert_time(duration) {
    var a = duration.match(/\d+/g);

    if (duration.indexOf('M') >= 0 && duration.indexOf('H') == -1 && duration.indexOf('S') == -1) {
        a = [0, a[0], 0];
    }

    if (duration.indexOf('H') >= 0 && duration.indexOf('M') == -1) {
        a = [a[0], 0, a[1]];
    }
    if (duration.indexOf('H') >= 0 && duration.indexOf('M') == -1 && duration.indexOf('S') == -1) {
        a = [a[0], 0, 0];
    }

    duration = 0;

    if (a.length == 3) {
        duration = duration + parseInt(a[0]) * 3600;
        duration = duration + parseInt(a[1]) * 60;
        duration = duration + parseInt(a[2]);
    }

    if (a.length == 2) {
        duration = duration + parseInt(a[0]) * 60;
        duration = duration + parseInt(a[1]);
    }

    if (a.length == 1) {
        duration = duration + parseInt(a[0]);
    }
    return duration
}

Fiddle