I'm trying to time a ajax request, but I get random elapsed time:
startTime = new Date();
$.ajax({
...
success: function(response){
endTime = new Date();
timeDiff = endTime - startTime;
elapsed = Math.round(timeDiff % 60);
alert(elapsed + ' seconds elapsed');
}
}
...Like after 2 seconds I get 36 seconds, or 59 seconds, or 1 second etc..
What am I doing wrong here?
Use / instead of %
% is modulo operator.
Proper code to calculate number of seconds between to dates:
(endTime.getTime() - startTime.getTime()) / 1000
Date - Date returns milliseconds. Lets say your request takes one second, so timediff = 1000. You then do a 1000 % 60, which is 40 and not what you want...
I think you want this:
elapsed = Math.round(timeDiff / 1000);
Which will convert milliseconds to seconds.
The modulo operator % return the remainder of a division operation which is not something you appear to be after...
Add a + sign to both versions of new Date():
startTime = +new Date();
That will guarantee that the date is converted into a numerical value (timestamp) which you can do the substraction operation with. It looks like it does work without, but I don't know what that will do some in browsers/versions implementations.
Also as mentioned in other answers, you need to divide the result (which is in miliseconds) by 1000 to get the seconds.
