Chapter 5. Scripting Mozilla- P2

Figure 5-2. Toggling the state of menu items in xFly

The following section explains more about hooking scripts up to the
interface. Needless to say, when you use a method like
getElementsByAttribute that operates on all elements with a
particular attribute value, you must be careful not to grab elements you
didn't intend (like a button elsewhere in the application that gets disabled for
other purpose).
Notes
[1]
You can use other DOM methods, but these methods are most
commonly used in the XPFE. Mozilla's support for the DOM is so
thorough that you can use the W3C specifications as a list of methods
and properties available to you in the chrome and in the web content the
browser displays. The full W3C activity pages, including links to the
specifications implemented by Mozilla, can be found at
http://www.w3.org/DOM/.
5.3. Adding Scripts to the UI
Once you are comfortable with how JavaScript works in the context of the
user interface layer and are familiar with some of the primary DOM methods
used to manipulate the various elements and attributes, you can add your
own scripts to your application. Though you can use other techniques to get
scripts into the UI, one of the most common methods is to use Mozilla's
event model, which is described in the next few sections.
5.3.1. Handling Events from a XUL Element
Events are input messages that pass information from the user interface to
the application code. Capturing this information, or event handling, is how
you usually tell scripts when to start and stop.
When the user clicks a XUL button, for instance, the button "listens" for the

script, there is a variation with the onchange handler attached to the
menulist element. onchange contains a JavaScript function call whose
definition may live in the XUL document itself or in an external file that is
included by using the src attribute on a script element:
<script type="application/x-javascript"
src="chrome://mypackage/content/myfile.js" />
A large basic set of event handler attributes is available for use on XUL
elements (and HTML elements). Appendix C
has a full listing of these
events along with explanations. The following subset shows the potential for
script interaction when the UI uses event handlers:
onabort
onblur
onerror
onfocus
onchange
onclick
oncontextmenu
ondestroy
onload
onpaint
onkeydown
onkeypress
onkeyup
onunload
onmousemove
onmouseout
onmouseover
onmouseup
onmousedown