function secsToTime(inputSecs){ 
    //convert time in seconds to human readable mm:ss 		
    var secs = Math.floor(inputSecs/1) % 60;
    var mins = Math.floor(inputSecs/60) % 60;
    var hours = Math.floor(inputSecs/3600);

    outTime = mins + ':' + secs;
    //add leading zeros
    outTime = outTime.replace(/\b(\d)\b/g, '0$1');
    
    if (hours){
        outTime = hours + ':' + outTime;
    }
    return outTime;
}
// console.assert(secsToTime('3600') == '1:00:00', 'Bad time format.');

function timeToSecs(time){ 
    //convert time in seconds to human readable mm:ss 		
    time = time.split(':');
    time = time.reverse();
    var multipliers = [1, 60, 3600];
    var secs = 0;
    for (var i=0; i < time.length; i++){
        secs += multipliers[i]*time[i];
    }    
    return secs;
}
// console.assert(timeToSecs("1:06:21") == 3981, 'Bad time conversion.');

setTimeRange = function(){
    var times = this.innerHTML.replace(/\s/g, '').split('-');
    var secsDif = timeToSecs(times[1]) - timeToSecs(times[0]);
    this.innerHTML = secsToTime(secsDif);
};
$(document).ready(function(){
    $('.timeRange').each(setTimeRange);
});