JSFiddle - React, Tailwind, and code Playground

JavaScript

var start_actual_time  =  "01/17/2012 11:20";
    var end_actual_time    =  "01/18/2012 12:25";

    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);