[Mediawiki-l] Signing text automatically in discussion page

[Tech Geek]

Magnus,

>A simple JavaScript could check if there's ~~~ in the edit box when
>saving a talk page, and alert you if there's not.
Looks like this might work. Where do you exactly put this javascript? Do I
have to install some kind of extension which will let me add my own
javascript or should I modify the main mediawiki files?

Thanks