I've recently submitted two patches (#5122 and #5266) to the Rails trac.
These patches are actually for Prototype. There appears to be very little
discussion about Prototype on this list, but I wanted to share what I've
been doing in the hopes of soliciting some feedback from you folks. If this
isn't the right place to discuss Prototype, mea culpa - where should I go?
http://dev.rubyonrails.org/ticket/5122
#5122 addressed adding document.getElementsByAttribute, alongside the
existing document.getElementsByClassName. We've found that while it's useful
to be able to use 'ByClassName, often we'll step on our designer's toes if
we try to use the class for a programmatic function. Semantically I believe
that the designer is right - the class attribute is for defining CSS
attributes, and not really intended for functionality.
Using document.getElementsByAttribute has changed how we approach our client
side scripting. We've taken to using custom attributes to group input
elements together to support domain specific functionality. For example, if
we have a column of text elements that are intended to be totalled, I will
set subtotal="true" inside those input elements. I can then assign an event
handler to all of these elements with one statement:
document.getElementsByAttribute('subtotal').each(function(obj) {
obj.onchange = handle_calc;
});
Seeing as any node can have multiple custom attributes defined, it is easy
to attach an arbitrary number of semantically named attributes which can be
iterated through as required. One huge advantage of this is that by DRYing
up your event handling code, you encourage moving past defining individual
event handlers on a per-node basis. Now, I have an init() function fire
which assigns all event handling and behavioural code; when you inspect the
source, all you see are intelligently named attributes.
http://dev.rubyonrails.org/ticket/5266
The second half of this is #5266, a modification to the .pluck method in
Prototype. Taken on its own, it might seem ho-hum, but when paired with
document.getElementsByAttribute, you have the tools you need to create
really potent domain specific solutions that don't require any further
inline event handling.
My favourite example is for an application where you need to keep track of
whether a change has been made on a page. Before you would have used a
relatively ugly combination of inline event handlers and javascript
variables. Instead, why not:
1. Attach changed="false" to every relevant node during the page render
2. Iterate through the document and assign the event handler for each node
with the changed attribute defined to a generic function that sets {
this.setAttribute('changed', 'true') }
3. When updating, set all nodes to changed='false'.
4. When leaving the page, iterate through the document using
document.getElementsByAttribute('changed').pluck('changed') and verify that
all nodes are changed = 'false', or else take appropriate action.
Many Rails coders will probably not feel the benefits of these changes right
away, but anyone using Prototype to do heavy client side work will likely
find this to be an awesome addition to their toolbox.
Pete
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