Adds the time in a youtube playlist

youtubePlaylistSize.js

timestamps = document.querySelectorAll("td.pl-video-time > div > div.timestamp > span")
var total = 0
for (i=0; i < timestamps.length; i++){
  var times = timestamps[i].innerHTML.split(":")
  for(j = 0 ; j < times.length ; j++){
    z = times.length - j - 1
    total += parseInt(times[z]) * Math.pow(60,j)
  }
}

var res = ""

timeDivisions = [60,60,24]
timeLetters = ['m','h','d']
for (i = 0; i < timeDivisions.length ; i++){
  if(total >= timeDivisions[i]){
    sub =  total % timeDivisions[i];
    res = timeLetters[i]+sub + res
    total = (total-sub)/timeDivisions[i]
  } else {
    break
  }
}
res = total + res+'s'
alert('total playing time = '+res)