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 23:00:00 .

Below I'm getting two time values from two dropdown menus and trying to calculate the difference in hours between the two times. I get wrong results...

Working example: http://jsfiddle.net/VnwF7/1/

Script:

$(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;            
        var diff_result = new Date(difference);    

        var hourDiff = diff_result.getHours();

        $("p").html("<b>Total Hours:</b> " + hourDiff )          
    }
    $("select").change(calculateTime);
    calculateTime();
});

HTML:

<select name="timestart">
<option value="00:00:00">12:00 am</option>
<option value="01:00:00">1:00 am</option>
<option value="02:00:00">2:00 am</option>
<option value="03:00:00">3:00 am</option>
<option value="04:00:00">4:00 am</option>
<option value="05:00:00">5:00 am</option>
<option value="06:00:00">6:00 am</option>
<option value="07:00:00">7:00 am</option>
<option value="08:00:00">8:00 am</option>
<option value="09:00:00">9:00 am</option>
<option value="10:00:00">10:00 am</option>
<option value="11:00:00">11:00 am</option>
<option value="12:00:00">12:00 pm</option>
<option value="13:00:00">1:00 pm</option>
<option value="14:00:00">2:00 pm</option>
<option value="15:00:00">3:00 pm</option>
<option value="16:00:00">4:00 pm</option>
<option value="17:00:00">5:00 pm</option>
<option value="18:00:00">6:00 pm</option>
<option value="19:00:00">7:00 pm</option>
<option value="20:00:00">8:00 pm</option>
<option value="21:00:00">9:00 pm</option>
<option value="22:00:00">10:00 pm</option>
<option value="23:00:00">11:00 pm</option>
</select>

<select name="timestop">
<option value="00:00:00">12:00 am</option>
<option value="01:00:00">1:00 am</option>
<option value="02:00:00">2:00 am</option>
<option value="03:00:00">3:00 am</option>
<option value="04:00:00">4:00 am</option>
<option value="05:00:00">5:00 am</option>
<option value="06:00:00">6:00 am</option>
<option value="07:00:00">7:00 am</option>
<option value="08:00:00">8:00 am</option>
<option value="09:00:00">9:00 am</option>
<option value="10:00:00">10:00 am</option>
<option value="11:00:00">11:00 am</option>
<option value="12:00:00">12:00 pm</option>
<option value="13:00:00">1:00 pm</option>
<option value="14:00:00">2:00 pm</option>
<option value="15:00:00">3:00 pm</option>
<option value="16:00:00">4:00 pm</option>
<option value="17:00:00">5:00 pm</option>
<option value="18:00:00">6:00 pm</option>
<option value="19:00:00">7:00 pm</option>
<option value="20:00:00">8:00 pm</option>
<option value="21:00:00">9:00 pm</option>
<option value="22:00:00">10:00 pm</option>
<option value="23:00:00">11:00 pm</option>
</select>

<p></p>

Answer 1

You can just subtract the hours right away doing it this way

var valuestart = $("select[name='timestart']").val();
var valuestop = $("select[name='timestop']").val();

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

var hourDiff = timeEnd - timeStart;             

Here's the working fiddle http://jsfiddle.net/VnwF7/4/

UPDATE - to calculate if we are including the next day. Just add the following if block

 if (hourDiff < 0) {
    hourDiff = 24 + hourDiff;
 }

http://jsfiddle.net/gfvhqat9/

Answer 2

try this way

var time_start = new Date();
var time_end = new Date();
var value_start = "06:00:00".split(':');
var value_end = "23:00:00".split(':');

time_start.setHours(value_start[0], value_start[1], value_start[2], 0)
time_end.setHours(value_end[0], value_end[1], value_end[2], 0)

time_end - time_start // millisecond 

Answer 3

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("<b>Hour Difference:</b> " + difference)             

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

Answer 4

It is not Jquery but everything related to time and date in JavaScript...

This might help: datejs http://code.google.com/p/datejs/

Here is some date and time calculation from the docs

 Date.today().set({ day: 15 })          // Sets the day to the 15th of the current month and year. Other object values include year|month|day|hour|minute|second.

        Date.today().set({ year: 2007, month: 1, day: 20 })


Date.today().add({ days: 2 })          // Adds 2 days to the Date. Other object values include year|month|day|hour|minute|second.

        Date.today().add({ years: -1, months: 6, hours: 3 })


Date.today().addYears(1)               // Add 1 year.
Date.today().addMonths(-2)             // Subtract 2 months.
Date.today().addWeeks(1)               // Add 1 week
Date.today().addHours(6)               // Add 6 hours.
Date.today().addMinutes(-30)           // Subtract 30 minutes
Date.today().addSeconds(15)            // Add 15 seconds.
Date.today().addMilliseconds(200)      // Add 200 milliseconds.

Date.today().moveToFirstDayOfMonth()   // Returns the first day of the current month.
Date.today().moveToLastDayOfMonth()    // Returns the last day of the current month.

new Date().clearTime()                 // Sets the time to 00:00 (start of the day).
Date.today().setTimeToNow()            // Resets the time to the current time (now). The functional opposite of .clearTime()

EDIT:Since this is a rather old answer I lately do also use moment.js for date related operations really useful, too. http://momentjs.com/ https://github.com/moment/moment/

Answer 5

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("<b>Hour Difference:</b> " + hourDiff )         
    }
    $("select").change(calculateTime);
    calculateTime();
});

Working fiddle

Answer 6

This code works for me, Code is written by considering the AM PM difference. Just write the date based on your favorite format and try this code

 function getTimeDifference(startTime, endTime) { const difference = endTime - startTime; const differenceInMinutes = difference / 1000 / 60; let hours = Math.floor(differenceInMinutes / 60); if (hours < 0) { hours = 24 + hours; } let minutes = Math.floor(differenceInMinutes % 60); if (minutes < 0) { minutes = 60 + minutes; } const hoursAndMinutes = hours + ":" + (minutes < 10? '0': '') + minutes; return hoursAndMinutes; } const start = new Date(0,0,0,23,15); const end = new Date(0,0,0,1,30); const difference = getTimeDifference(start, end); console.log(difference);