IFrame (from inline frame) is an HTML element which makes it possible to
embed another HTML document inside the main document.
The size of the IFrame is specified in the surrounding HTML page, so that the surrounding page can already be presented in the
browser while the IFrame is still being loaded. The IFrame behaves much like an inline image and
the user can scroll it out of view. On the other hand, the IFrame can contain its own scroll
bar, independent of the surrounding page's scroll bar.
While regular frames are typically used to logically subdivide the content
of one website, IFrames are more commonly used to insert content (for instance an advertisement)
from another website into the current page.
The following is an example of an HTML document containing an IFrame:
<html>
<head>
<title>Inline Frames - demonstration</title>
</head>
<body>
The material below comes from the website http://example.com:
<iframe src="http://example.com"
height="100" width="200" frameborder="0" scrolling="no">
Alternative text for browsers that do not understand IFrames.
</iframe>
</body>
</html>
The embedded document can be replaced with a different one without reloading the surrounding page, by using the "target"
attribute of an HTML anchor or by employing JavaScript.
This makes many interactive applications possible, and IFrames are therefore commonly
used by Ajax applications (this is a combination of Asynchronous Javascript and XML
languages). The main alternative to using an IFrame in these situations is editing a document's DOM tree. Sometimes invisible IFrames are also used for asynchronous communication with the
server, as an alternative to XMLHttpRequest.
More recently, Mozilla Firefox, Opera
and Microsoft Internet Explorer introduced contentEditable and
designMode, which enables users to edit the contents of the HTML contained in an IFrame. This feature has been used
to develop rich text (WYSIWYG) editors within an IFrame element like FCKeditor. Popular web applications which make use of this feature include Google Docs & Spreadsheets (formerly Writely), JotSpot Live, and
MSN Hotmail to name a few.
External links
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