Accessing DOM node information via RJS

Rails
1

I have been pulling my hair out for way too long on this…and it seems
so trivial! The following does not work:

if page[‘test’].className == “whatever”
page[‘test’].className = “whatever2”
end

Now that I write this post, I realize why it doesn’t work - className is
a value in the Javascript code - not in Rails. But, is there any way to
access the className value in the IF statement?

Thanks,
Vishal

2

I have been pulling my hair out for way too long on this…and it seems
so trivial! The following does not work:

if page[‘test’].className == “whatever”
page[‘test’].className = “whatever2”
end

Now that I write this post, I realize why it doesn’t work - className is
a value in the Javascript code - not in Rails. But, is there any way to
access the className value in the IF statement?

select maybe?

http://api.rubyonrails.org/classes/ActionView/Helpers/PrototypeHelper/JavaScriptGenerator/GeneratorMethods.html#M000430

select(pattern)

Returns a collection reference by finding it through a CSS pattern in
the
DOM. This collection can then be used for further method calls.
Examples:

page.select(‘p’) # => $$(‘p’);
page.select(‘p.welcome b’).first # => $$(‘p.welcome b’).first();
page.select(‘p.welcome b’).first.hide # => $$(‘p.welcome
b’).first().hide();

You can also use prototype enumerations with the collection. Observe:

page.select(‘#items li’).each do |value|
value.hide
end

=> $$(‘#items li’).each(function(value) { value.hide(); });

Though you can call the block param anything you want, they are always
rendered in the javascript as .value, index… Other enumerations, like
collect() return the last statement:

page.select(‘#items li’).collect(‘hidden’) do |item|
item.hide
end

=> var hidden = $$(‘#items li’).collect(function(value, index) {

return value.hide(); });

3

Nope…After perusing through some message boards, it seems that RJS
does not currently have the ability to use Ruby conditional logic. =(

4

Are you trying to update the style class of a specific node or all of
the
nodes containing a particular class?

Is the RJS returned from a specific AJAX function link from the node you
are
interested in? You could use the :with attribute to pass in the style
class
name if this is the case.

On 10/4/06, Vishal A. [email protected] wrote:

Nope…After perusing through some message boards, it seems that RJS
does not currently have the ability to use Ruby conditional logic. =(

–
Posted via http://www.ruby-forum.com/.

–
Thanks,
-Steve
http://www.stevelongdo.com

5

Vishal A. wrote:

I have been pulling my hair out for way too long on this…and it seems
so trivial! The following does not work:

if page[‘test’].className == “whatever”
page[‘test’].className = “whatever2”
end

Now that I write this post, I realize why it doesn’t work - className is
a value in the Javascript code - not in Rails. But, is there any way to
access the className value in the IF statement?

Yeah, there’s a fundamental misunderstanding going on here. When you
write an RJS template, you’re not writing Ruby that communicates ‘live’
with Javascript on the web browser. The entire RJS template is
converted to Javascript on the server, and is then sent in one big lump
to the web browser, where it is run.

Therefore, you cannot do anything in RJS that involves ‘reading’
something about the state of the browser or document. Or in other
words, the entire RJS template has to make sense without any knowledge
of what’s going on in the browser/document.

I’d just drop into Javascript for this kind of thing.

Chris

6

On 5 October 2006 12:51, Chris M. wrote:

access the className value in the IF statement?
of what’s going on in the browser/document.

I’d just drop into Javascript for this kind of thing.
Yet, there is a solution. I had the very same problems and have written
a
simple plugin that allows something like this:

page.if page[‘test’].hasClassName(‘whatever’) do
page[‘test’].classNames.set(‘whatever’)
end

You can install it with this command:
./script/plugin install
svn://rubyforge.org/var/svn/js-if-blocks/trunk/js-if-blocks