JSFiddle - React, Tailwind, and code Playground

HTML

<input id="start" value="01/17/2012 11:20" />
<input id="end" value="01/17/2012 11:20" />
<input id="result" value="Result" />

JavaScript

var start_actual_time  =  $("#start").val(text);
    var end_actual_time    =  $("#end").val(text);

    start_actual_time = new Date(start_actual_time);
    end_actual_time = new Date(end_actual_time);

    var diff = end_actual_time - start_actual_time;

    var diffSeconds = diff/1000;
    var HH = Math.floor(diffSeconds/3600);
    var MM = Math.floor(diffSeconds%3600)/60;

    var formatted = ((HH < 10)?("0" + HH):HH) + ":" + ((MM < 10)?("0" + MM):MM)
    alert(formatted);