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

I changed your code to just use the difference without having to create another date object:

$(document).ready(function() {    
function calculateTime() {
        //get values
        var valuestart = $("select[name='timestart']").val();
        var valuestop = $("select[name='timestop']").val();

         //create date format          
         var timeStart = new Date("01/01/2007 " + valuestart);
         var timeEnd = new Date("01/01/2007 " + valuestop);

         var difference = timeEnd - timeStart;             

         difference = difference / 60 / 60 / 1000;


    $("p").html("Hour Difference: " + difference)             

}
$("select").change(calculateTime);
calculateTime();
});​