11.2 Frame Tags

11.2 Frame Tags

You need to know only three tags to create a frame document: <frameset>, <frame>, and <noframes>. In addition, the HTML 4 and XHTML standards provide the <iframe> tag, which you may use to create inline, or floating, frames.

A frameset is simply the collection of frames that make up a browser's window. Column- and row-definition attributes for the <frameset> tag let you define the number and initial sizes for the columns and rows of frames. The <frame> tag defines which document — HTML or otherwise — initially goes into the frames within those framesets and is where you may give the frame a name to use for document hypertext links.

Here is the HTML source used to generate Figure 11-1:

<html>
<head>
<title>Frames Layout</title>
</head>
<frameset rows="60%,*" cols="65%,20%,*">
  <frame src="frame1.html">
  <frame src="frame2.html">
  <frame src="frame3.html" name="fill_me">
  <frame scrolling=yes src="frame4.html">
  <frame src="frame5.html">
  <frame src="frame6.html" id="test">
  <noframes>
    Sorry, this document can be viewed only with a 
    frames-capable browser.
    <a href = "frame1.html">Take this link</a>
    to the first HTML document in the set.
  </noframes>
</frameset>
</html>

Notice a few things in the simple frame example and its rendered image (Figure 11-1). First, like tables, frames in a frameset are filled row by row by the browser. Second, Frame 4 sports a scrollbar because we told it to, even though the contents may otherwise fit without scrolling. (Scrollbars automatically appear if the contents overflow the frame's dimensions, unless explicitly disabled with the scrolling attribute in the <frame> tag.) This works for Internet Explorer and earlier versions of Netscape, but Netscape Version 6 displays the scrollbar only when the contents overflow the frame and scrolling is not explicitly disabled. [<frame>]

Another item of interest is the name attribute in the example frame tags. Once named,^[1] you can reference a particular frame as the location in which to display a hypertext-linked document or perform some automated action. To do that, you add a special target attribute to the anchor (<a>) tag of the source hypertext link. For instance, to link a document called new.html for display in Frame 3, which we've named "fill_me," the anchor looks like this:

^[1] But, interestingly, not id'd, even though the attribute exists for frames and can identify other HTML/XHTML elements as hyperlink targets.

<a href="new.html" target="fill_me">

If the user chooses the link, say in Frame 1, the new.html document replaces the original frame3.html contents in Frame 3. [Section 11.7.1]

Finally, although Netscape and Internet Explorer both support frames, it is possible that users with some other browser will try to view your frame documents. That's why each of your key frame documents should provide a back door to your document collection with the <noframes> tag. Frames-capable browsers display your frames; non-frames-capable browsers display the alternative <noframes> content.

11.2.1 What's in a Frame?

Anyone who has opened more than one window on their desktop display to compare contents or operate interrelated applications knows instinctively the power of frames.

One simple use for frames is to put content that is common in a collection, such as copyright notices, introductory material, and navigational aids, into one frame, with all other document content in an adjacent frame. As the user visits new pages, each loads into the scrolling frame, while the fixed-frame content persists.

A richer frame document-enabled environment provides navigational tools for your document collections. For instance, assign one frame to hold a table of contents and various searching tools for the collection. Have another frame hold the user-selected document contents. As users visit your pages in the content frame, they never lose sight of the navigational aids in the other frame.

Another beneficial use of frame documents is to compare a returned form with its original for verification of the content by the submitting user. By placing the form in one frame and its submitted result in another, you let the user quickly verify that the result corresponds to the data entered in the form. If the results are incorrect, the form is readily available to be filled out again.