Calculate Time Difference with JavaScript

Question

I have two HTML input boxes, that need to calculate the time difference in JavaScript onBlur (since I need it in real time) and insert the result to new input box.

F

Answer 1

TimeCount = function()
{
    t++;
    var ms = t;
    if (ms == 99)
    {
        s++;
        t = 0;
        if ( s == 60)
        {
            m++;
            s = 0;
        }
    }

    Dis_ms = checkTime(ms);
    Dis_s = checkTime(s);
    Dis_m = checkTime(m);
    
    document.getElementById("time_val").innerHTML = Dis_m + ":" + Dis_s+ ":" + Dis_ms;
}

function checkTime(i) 
{
  if (i<10) {
    i = "0" + i;
  }
  return i;
}