Difference between two Dates

The diffDate() function takes a start date and an end date and returns the human readable form. For example : 41 mins, 53 secs

var varStartDate = new Date();
// Do some things here
var varEndDate = new Date();

var varTotalTime = diffDate(varStartDate, varEndDate);
print (varTotalTime);

function diffDate (startDate, endDate)
{
    var varRegex_Time = new RegExp("^(.+?)\\.(.+)$");
    var varRegex_Truncate = new RegExp("^\\, (.+)$");
    varStart = (startDate != undefined) ? startDate.getTime() : 0;
    varEnd = (endDate != undefined) ? endDate.getTime() : 0;
    diff  = varEnd - varStart;
    secs  = Math.floor(diff / 1000 % 60);
    mins  = Math.floor(diff / (1000 * 60) % 60);
    hours = Math.floor(diff / (1000 * 60 * 60) % 24);
    days  = Math.floor(diff / 86400000);
    secsText  = (secs  > 1) ? ", " + String(secs).replace(varRegex_Time, "$1") + " secs" : "";
    minsText  = (mins  > 1) ? ", " + String(mins).replace(varRegex_Time, "$1") + " mins" : "";
    hoursText = (hours > 1) ? ", " + String(hours).replace(varRegex_Time, "$1") + " hours" : "";
    daysText  = (days > 1)  ? String(days).replace(varRegex_Time, "$1") + " days" : "";
    return String(daysText + hoursText + minsText + secsText).replace(varRegex_Truncate, "$1");
}