Imaginary Landscape open-sourced some work I did recently on a Javascript library for handling repeating elements in forms. I've rewritten it more than once since then, and might just rewrite it again before it settles down.

After the last rewrite it more-or-less follows the WHAT-WG Web Forms 2.0 spec with respect to repeating forms. The implementation practically falls out of the spec, so after I just read it closely it was pretty clear how to implement it. Though, having implemented it, I need to bring some questions back to the WHAT-WG group -- especially related to moving repetition blocks around.

Conveniently, the spec works very well with FormEncode and variabledecode in particular. But it's actually expedience that made me implement it in the first place. Without repeating form elements, you have to have multiple complex forms, with lots of add/edit/delete functionality. With repeating forms you just have a single form, and the update is a single HTTP request. Less templates, less things to explain, less controllers, and a better user experience to boot.

I still have to figure out where this will go. I like MochiKit, but I've ended up factoring out nearly all the MochiKit dependencies (not because I was trying, it just happened). And it also fits a somewhat different style -- the Javascript is largely implicit, based on declarative HTML as defined in the spec. A big feature of the Web Forms 2.0 spec (IMHO) is that it isn't expressed in Javascript, and you don't have to think about Javascript while using it.

OTOH, I have no desire to set up a separate project or deal with any of that. I'd much rather glom onto someone else's project ;)

I've seen other implementations of portions of WHAT-WG. But they all seem complicated, or tied to one browser. (Well, I haven't tested on IE yet, but that's incidental.) That seems unnecessary, because at least large portions of Web Forms 2.0 is pretty simple Javascript. Plus I have a hard time finding them.

Anyway, the files are temporarily located at http://svn.colorstudy.com/home/ianb/repeat_form and a demo at http://ianbicking.org/examples/repeat_form/form.html