function toms(mmss) {
  if(typeof mmss !== 'string') {
    if(mmss.toString) mmss = mmss.toString();
    else throw("Invalid input");
  }

  var parts = mmss.split(':')
    ,n = parts.length
    ,ms = 0
    ,i
  ;

  for(i = 0; i < parts.length; i++) {
    part = parseInt( parts[n - 1 - i]);
    if(i === 0) {
      ms += part * 1000;
    } else if(i === 1) {
      ms += part * 6e4;
    } else if(i === 2) {
      ms += part * 36e5;
    }
  }

  return ms;
}

toms('01:12')    // 72000
toms('01:02:03') // 3723000
toms(55)         // 55000

let time = "03:50";
    let time_parts = time.split(":");
    let millisecond = time_parts[0] * (60000 * 60)) + (time_parts[1] * 60000);

var time_parts = timeTotal.split(":");

var minutes = (time_parts[0] * 60000);
var millisecond = (time_parts[1] * 1000);

var result = minutes + millisecond;