Question: I've written a Javascript file, using jQuery, that I would like to perform run-time tests on. I've never done this before and was just curious on how to go about it. One site I visited suggested this as a measurement:

```
var start = (new Date).getTime();
/* Run a test. */
var diff = (new Date).getTime() - start;

```

This makes sense, right now my script is acting on a web page, all it does is sort clicked-on columns in a table. What I'm interested in knowing, besides the actual timings, is how to interpret the timings in Big-O notation. Also, is this the most standard method of measuring script run-times? Your thoughts are appreciated.

UPDATE:
Thanks guys for your input, installed Firebug and am playing with the profiler. I'll attempt to see if I can come up with an approximation to check the timings against for Big-O notation.

Answer: 
Install firefox with [firebug](http://getfirebug.com/), then add `console.time('anyTimerYouWant');` to start the timer and `console.timeEnd('anyTimerYouWant');` to end it.

BigO notation cannot be easily programmatically calculated as far as I know.
I'm not sure what the purpose of your code is but I would not try to infer big O notion analysis from actually timing the code. The whole idea of big O notion is the the asymptotic number of steps as a factor of n, your input. Sorting algorithms are bigger or equal to O(n\*log(n)), so it can't be O(n). BTW, when numbers are not big enough it is very hard to tell O(n) from O(n\*log(n)).