Time Difference in format 'HOUR:MONTH'

timDiff.js

/**
 * Time Difference
 * 
 * function   :  timeDiff(t1, t2) 
 * timeformat : 'HOUR:MINUTES'
 * 
 */

function timeInHours(str)
{
    var sp = str.split(":");
    return parseInt(sp[0], 10) + parseFloat(sp[1]/60, 10);
}

function hoursToString(h)
{
    var hours = Math.floor(h);
    var minutes = Math.round((h - hours)*60);

    return hours + ":" + minutes;
}

function timeDiff(t1, t2)
{
    var st1 = timeInHours(t1);
    var st2 = timeInHours(t2);

    if (st1 > st2) {
        return hoursToString(timeDiff(t1, "24:00") + timeDiff("00:00", t2));
    }

    return hoursToString(st2 - st1);
}