Where, or if you prefer when, is this code executed?

To be precise, what event* do you use to execute the function?

I ask that because, (I'll go out on a limb here) the code may be being executed as the page loads, but (perhaps) the script can only function correctly when the page is loaded fully. Forcing you to answer a modal message box {via alert()} causes the execution of the remainder of the function to be temporarily paused, meaning that when the important parts of the function are executed, the page has loaded.

Like I hope that I implied, that's an assumption founded on a working knowledge rather than any practical tests or even directly related experience**. The easiest way to find out if this is the case is to try putting the alert() after the function's main body, and posting back what happens.

Also; do say where the code is called from/when it is called.

*'inside script tags' is a viable event of sorts.
**or infact, a complete understanding of what you're trying to achieve. If you're calling this function from a user invoked event (like a click) on a fully loaded page; I have no idea.