Hi,
On Oct 8, 6:30 pm, Walter Lee Davis <[email protected]> wrote:
> What's a more idiomatic way to write this:
>
> Element.addMethods({
> toggleClassName: function(element, className){
> var element = $(element);
> (element.hasClassName(className)) ?
> element.removeClassName(className) : element.addClassName(className);
> return element;
> }
>
> });
>
> This works, but it's got that really long line in the middle. How do you do
> what PHP calls a "variable variable" in JavaScript to execute the correct
> method (add/remove) based on the input without writing it all out long-hand?
>
> Walter
You are aware that Prototype *has* `toggleClassName` already[1],
right? And in fact, I think the current implementation of it answers
your question about "variable variables":
toggleClassName: function(element, className) {
if (!(element = $(element))) return;
return Element[Element.hasClassName(element, className) ?
'removeClassName' : 'addClassName'](element, className);
},
That works because as you probably know, you can refer to an object
property using a literal with dotted syntax:
x = obj.foo;
...or with a string using bracketed syntax:
x = obj['foo'];
The latter opens up the possibility of using an expression for the
string:
x = obj[flag ? 'foo' : 'bar'];
And of course, what we think of as methods aren't really methods at
all[2], they're just functions assigned to properties, and so:
obj[flag ? 'foo' : 'bar']();
...will call `obj.foo()` or `obj.bar()` depending on the value of
`flag`. That's what the Prototype version of `toggleClassName` does,
it calls `removeClassName` or `addClassName` based on the result of
calling `hasClassName`.
This form of "variable variables" only works with object properties,
but I find that it applies in 99% of the situations I'd want it.
[1] http://api.prototypejs.org/dom/Element/toggleClassName/
[2] http://blog.niftysnippets.org/2008/03/mythical-methods.html
HTH,
--
T.J. Crowder
Independent Software Engineer
tj / crowder software / com
www / crowder software / com
--
You received this message because you are subscribed to the Google Groups
"Prototype & script.aculo.us" group.
To post to this group, send email to [email protected].
To unsubscribe from this group, send email to
[email protected].
For more options, visit this group at
http://groups.google.com/group/prototype-scriptaculous?hl=en.
