Referencing Windows
By: aathishankaran Printer Friendly Format
When working with single and multiple frames in your
JavaScript application, you probably need to use additional ways to reference
windows. JavaScript provides four references to windows. Each of the references
are implemented as properties of the window object.
Window
and self
User can refer to the current window as window or self.
For example, the following two code lines are functionally the same:
window.defaultStatus = "Welcome to the
Goat Farm Home Page"
self.defaultStatus = "Welcome to the
Goat Farm Home Page"
Because both window and self are synonyms to
the current window, you might find it curious that both are included in the
JavaScript language. As shown in the previous example, the rationale is simply
flexibility; you can use window or self as you want.
However, as useful as window and self can be, it can
easily become confusing to think about the logic behind it all. After all, an
object's property that is used as an equivalent term for the object itself is
rather unusual. Consequently, you might find it helpful to think of window or
self as "reserved words" for the window object rather than its
properties.
Because window and self are properties of
the window object, you cannot use both window and self in the same context. For
example, the following code does not work as desired:
window.self.document.write("< hl
>Test. </hl >")
Finally, in multiframe environments, window and self
always refer to the window in which the JavaScript code is executed.
Parent
Frames are the same as window objects within a frameset.
Within this multi-frame setting, you need to distinguish between the various
frames displayed in the browser. The parent property of a window object helps
you do that by referencing it’s parent-the window containing the
<FRAMESET> definition. For example, if you want to retrieve some
information about the current window's parent, you use the following example in
Listing.
<html>
<head>
<title>Child Window</title>
</head> <SCRIPT
LANGUAGE=â€JavaScriptâ€>
<!- function getParentInfo()
{
myParentTitle = parent.document.title
alert(“My daddy's name is “ + myParentTitle)
}
//->
</ SCRIPT>
<form>
<input type=â€button†value=â€Get Infoâ€
onClick=â€getParentInfo () “>
</form>
</body>
</html>
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