14.2. Introduction to Frames
Frames allow you to divide the browser window into smaller subwindows, each of which displays a different HTML document. Introduced by Netscape Navigator 2.0, frame support was soon added by other popular browsers. The basic frame specification works with Netscape Navigator 2.0 and higher as well as Microsoft Internet Explorer 3.0 and higher. As of this writing, frames have found their way into the World Wide Web Consortium's HTML 4.01 specification.
Despite the advanced navigational functionality that frames offer, they do present certain problems and peculiarities that have lead to their currently controversial status. In fact, they've become so notorious that it is not uncommon for web developers to encounter clients who, despite not knowing a lick of HTML themselves, strongly proclaim, "No frames!" at the beginning of a project.
Like most things, frames are neither all good nor all bad. It is your responsibility to be familiar with both sides of the coin so you can help present the best solution for your clients' needs.
14.2.1. Advantages
Consider these advantages to using frames:
-
The main advantage to frames is that they enable parts of the page to remain stationary while other parts scroll. This is useful for elements you may not want to scroll out of view, such as navigational options or banner advertising.
-
Frames unify resources that reside on separate servers. For instance, you may use frames to combine your own material (and navigation graphics) with threaded discussion material generated by software on a vendor's server.
-
With the <noframes> tag, you can easily add alternative content for browsers that do not support frames. This degradability is built into the frames system.
14.2.2. Disadvantages
Also keep in mind these disadvantages:
-
Frames are not supported by some browsers. (<noframes> may address this problem.)
-
Frames may make site production more complicated because you need to produce and organize multiple files to fill one page.
-
Navigating through a framed site may be prohibitively challenging for some users (especially users with disabilities who are using alternative browsing devices).
-
Documents nested in a frameset may be more difficult to bookmark. Bookmarks identify only the top-level framed document in its initial state; there is currently no way to track the states of a frameset and therefore no way to bookmark individual states. There are workarounds in 4.0 browsers, however, such as opening the contents of the frame in a new window and bookmarking that page.
-
A large number of frames on a page may significantly increase the load on the server because so much of the load on a server is initial document requests. Four requests for 1K files (the frameset and the contents of three frames) is more work for your server than a single request for a 4K document.
-
Framed documents can be a nuisance for search engines. Content-level documents may be missed in searches. If a contained document is found by a search engine, it will probably be displayed out of context of its frameset, potentially losing important navigational options. For more information on searching framed documents, see Section 14.7.3, "Helping Search Engines" later in this chapter.
-
It is more difficult to track actual page (or ad) impressions when the pages are part of a framed document.
That said, let's look at how framed documents are constructed.
 |  |  |
| 14. Frames |  | 14.3. Basic Frameset Structure |
Copyright © 2002 O'Reilly & Associates. All rights reserved.