JavaScript Examples Bible - UserWorks Technologies

Chapter 1 ✦ Generic HTML Element Objects (Chapter 15)
default color (“red”) or any other color that is passed to the component. For details
on the syntax of the tags, see Chapter 48 of the JavaScript Bible. The code
presented here helps you see how the page and scripts in Listing 15-19b work.
Listing 15-19a: The makeHot.htc Behavior Component
var oldColor
var hotColor = “red”
function setHotColor(color) {
hotColor = color
}
function makeHot() {
if (event.srcElement == element) {
oldColor = style.color
runtimeStyle.color = hotColor
}
}
function makeNormal() {
if (event.srcElement == element) {
runtimeStyle.color = oldColor
}
}
The object to which the component is attached is a simple paragraph object,
shown in Listing 15-19b. When the page loads, the behavior is not attached, so
clicking the paragraph text has no effect.
When you turn on the behavior by invoking the turnOn() function, the
addBehavior() method attaches the code of the makeHot.htc component to the
myP object. At this point, the myP object has one more property, one more method,
and two more event handlers that are written to be made public by the component’s
code. If you want the behavior to apply to more than one paragraph in the document,
you have to invoke the addBehavior() method for each paragraph object.
After the behavior file is instructed to start loading, the setInitialColor() function
is called to set the new color property of the paragraph to the user’s choice from
the SELECT list. But this can happen only if the component is fully loaded. Therefore,
the function checks the readyState property of myP for completeness before invoking
the component’s function. If IE is still loading the component, the function is
invoked again in 500 milliseconds.
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elementObject.addBehavior()