How can I calculate the difference between two times that are in 24 hour format?

Question

In JavaScript, how can I calculate the difference between two times that are in 24 hour format?

Example: Get how many hours elapsed from 08:00:00 to

Answer 1

You dont need to convert them into dates for this specific case. Just Do this

$(document).ready(function() {    
    function calculateTime() { 
        var hourDiff = 
        parseInt($("select[name='timestart']").val().split(':')[0],10) -         
        parseInt($("select[name='timestop']").val().split(':')[0],10);

        $("p").html("Hour Difference: " + hourDiff )         
    }
    $("select").change(calculateTime);
    calculateTime();
});

Working fiddle​