Drupal 6 JavaScript and jQuery - Ebook-Cours.com

Drupal Behaviors
For example, let's look at another behavior that we assume would work with the one
we just created:
Drupal.behaviors.countParagraphs = function (context) {
if ($('#lots', context).size() > 0) {
return;
}
else if ($('p', context).size() > 5) {
$('body').append('Lots of Text!');
}
};
The previous code snippet does the following:
• It checks to see if an element with the ID lots exists. If it does, that means
this behavior has already been properly processed. So it returns early.
• If the lots ID does not exist, it checks to see if there are more than
five paragraphs.
• If there are more than five paragraphs, a short piece of text Lots of Text!is
appended to the end of the document. The ID of the paragraph that wraps
this text is lots. So we know this has already been processed (and that there
are more than five paragraphs) by the existence of the lots ID.
Another important thing to notice is that both queries (the checking queries) use the
context. This is the recommended procedure, but it can have unanticipated results, as
we shall see.
We have two behaviors, both making use of the context in the recommended way. In
our code that attaches the new paragraph we call attachBehaviors(), passing it the
most narrow context we can (the paragraph that was inserted).
So what happens when the number of paragraphs in the document exceeds
five? Nothing.
Here's an example from Firebug's console:
>>> $('p').size();
5
>>> var cxt = $('Sixth paragraph')
.appendTo('body').get(0);
>>> Drupal.attachBehaviors(cxt);
>>> $('p').size();
6
>>> $('#lots').size();
0
[ 100 ]
This material is copyright and is licensed for the sole use by Richard Ostheimer on 18th June 2009
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