rocknbil - 4:54 pm on Mar 17, 2011 (gmt 0)

Could you clarify your definition of a pop-up? Automatically generated pop ups are the windows that load without anyone's action, these are the ones that are the scourge of the web. Unfortunately, javascript generated new windows have been lumped in with these. Some good examples are a help pop up or other supplemental information that can be accessed and is not enough to warrant it's own full page, and is only accessed when the user clicks a link - thereby providing his or her "permission" to access the document.

In the first case, seems like a chicken and an egg, how can you give them the option to decline without throwing some alert or pop up itself?

In the second case, as ergo says, some approaches render the content inaccessible as it doesn't work if Javascript is disabled:

<a href="javascript:popUp(somefile.html)">
<a href="#" onclick="popUp(somefile.html);">

Easily fixed . . .

<a href="somefile.html" onclick="return popUp(somefile.html);">

You'd return false from the popUp function which is what stops the page from navigating to somefile.html (or top of the page in the case of #.)