What is wrong with this Greasemonkey script?

June 6, 2009 12:59 PM

What is wrong with this Greasemonkey script?

I just installed Greasemonkey for the first time, and I've started trying to figure out how to create Greasemonkey scripts, but I can't seem to get it to actually insert anything into the HTML. For example, I got the following very basic script from this tutorial page:

var elmNewContent = document.createElement('div');
document.body.appendChild(elmNewContent);

I would expect that this should insert an empty <div> into the page's HTML (for a page in the "include" list, and not in the "exclude" list), but it doesn't.

The script is definitely running on the appropriate page; for example, if I instead do this:

alert('start');
var elmNewContent = document.createElement('div');
document.body.appendChild(elmNewContent);
alert('end');

I do get the "start" and "end" message boxes. Similarly, I can issue log messages to the console via GM_log.

I've installed the Mefi deleted posts script, just to see if some "real" script works, and it does.

I've also tried insertBefore instead of appendChild; this doesn't help.

The console doesn't show any error messages or anything.

This is for Firefox 3.0.10.0, and Greasemonkey 0.8.20090123.1.

Thanks for any help!

posted by Flunkie to Computers & Internet (2 answers total)

Best answer: How do you know if an empty div is not being inserted?

If you are using View > Page Source in Firefox, that will not show any elements added by GreaseMonkey. You need to view the 'generated' source -- the Web Developer extension is useful here, and a less reliable alternative is selecting, right-clicking and choosing View Selection Source.

If you try adding a div with some content, does it show up?
posted by matthewr at 1:26 PM on June 6, 2009

Response by poster:

How do you know if an empty div is not being inserted?

Ummmm... by looking at View / Page Source....

That was it! Thanks very much.
posted by Flunkie at 1:32 PM on June 6, 2009