How to measure code execution time in VBScript or JavaScript?

Question

What is a good way to measure code execution time in VBScript?

Or failing that how to do it in JavaScript?

Answer 1

For JavaScript, use the Firebug or IE profilers, or free DynaTrace AJAX edition profiler.

Answer 2

This really depends on what you are trying to measure?

If are testing something and want to know how long certain pieces go, you could just declare a start and stop time variable, then do a difference between them....

Answer 3

d=new Date(); x=0; for (i=0; i < 1e7; ++i) { x += i; } d2=new Date(); d2-d

12296

Use the Date object, which returns a valueOf() in milliseconds since Jan 1 1970. You can then subtract times to get elapsed time in milliseconds.

Answer 4

For JavaScript, I would recommend you to use a profiler, like the one built-in in Firebug:

Other alternatives can be the one included with Google Chrome, or IE8

If you want to do it programmatically, you could use Date objects to get a time difference:

var startTime = new Date();
// ...
// ...
var endTime = new Date();
var delta = endTime - startTime; // difference in milliseconds

Answer 5

For VBScript you can use Timer:

StartTime = Timer()
EndTime = Timer()
Response.Write("Seconds to 2 decimal places: " & FormatNumber(EndTime - StartTime, 2))

Or ASP Profiler (that is for an ASP environment.)

For JavaScript you can use Date:

var start = new Date().getTime()
alert("Milliseconds: " + (new Date().getTime() - start))

Firebug also has a profiler for JavaScript.

Answer 6

This is a great article on JavaScript timing, from the book "Even Faster Websites". Two things to keep in mind are that JavaScript Date objects often have a resolution as big as 15ms (this varies by browser and operating system), and most profilers have an observer effect. Note that Google Speed Tracer (new since the article was published) runs out of process and collects data asynchronously to minimize the observer effect.