Create Custom Pseudo Class Selectors Using the Slick Selector Engine
As I mentioned in my previous post about the Slick selector engine, Create Elements on the Fly with MooTools 1.3 and Slick, Slick is extremely flexible. Part of that flexibility is the ability for you to define custom pseudo class selectors to better gather the elements that meet your needs.
It all starts with the Slick.definePseudo method; just give Slick.definePseudo the name of your pseudo class selector and a function returning true (matched) or false (not a match).
The Slick JavaScript
Slick.definePseudo('key',function(optionalArgument) {
var trueOrFalse;
// logic here to determine if there is a match
return trueOrFalse;
})
The above code sample displays the basic format of defining a custom pseudo class selector. Let's create a few "realistic" pseudo class selectors.
Elements with a Storage Value
Slick.definePseudo('storage',function(key) {
return document.id(this).retrieve(key);
});
The above code sample allows you to find elements with a given storage value based on the provided key.
Elements with a Specified Event Type
Slick.definePseudo('hasEvent',function(eventType) {
var self = document.id(this);
return eventType &&
self.retrieve('events') &&
self.retrieve('events')[eventType] &&
self.retrieve('events')[eventType].length;
});
The above code sample allows you to find elements with a MooTools-given click event.
Form Elements
Slick.definePseudo('form',function() {
var tag = document.id(this).get('tag'), elements = ['textarea','select','input','button']
return elements.contains(tag);
});
The above code sample allows you to get all form elements within a given form.
Those are just a few examples of creating your own custom pseudo class selectors. Another great thing about Slick is that numerous psuedo class selectors are already defined: empty, not, contains, first-child, last-child, only-child, nth-child, nth-last-child, nth-of-type, nth-last-of-type, index, even, odd, first-of-type, last-of-type, only-of-type, enabled, disabled, checked, and selected.
Slick comes bundled with MooTools 1.3 but do remember that Slick is framework-independent an can function on its own. Can you think of any other pseudo class selectors that would be useful? Share them!
I should mention that I am mixing MooTools within the pseudo class selectors. You can easily mix jQuery or any other library functionalities in too!
I find myself repeatedly doing things like this in 1.2. The Slick code with 1.3 is …well…slick!
This method coupled with the new HTML 5 elements will make our code much more readable.
Just to clarify: E.g. from the Storage Value example, when you’ve stored a value:
element.store('storage','picture');Then, after calling Slick.definePseudo(…), you could in the future retrieve it and all elements with the same storage value by:
$$(':picture').each(...);Is that roughly the idea?
Be carefull cause these functionality are used in a loop so you should always optimize it as much as possible. Try not to use document.id on “this” (if its not necessary of course) for example.
@Fábio Miranda Costa: For simple stuff, yes.
You should provide a usage example for each selector you defined. This article is still relevant and I bet will stay relevant for a while, so enhance it.
Otherwise, useful and cool! :)