Minute difference between two arbitrary string values

CountingMinutesI.js

function CountingMinutesI(str) { 
  var times = str.replace(";\"","").split("-").map(function(t) {
    t = t.split(":");
    var h = parseInt(t[0], 10);
    var m = parseInt(t[1], 10);
    var am = t[1].indexOf("am") > 0;
    if(h === 12) h = 0;
    var mins = m + h * 60;
    if(!am) mins += 720;
    return mins;
  });
  var diff = times[1] - times[0];
  return diff > 0 ? diff : diff + 1440;          
}

Use it like:
CountingMinutesI("12:05am-02:55pm")