Section 14.1. Introduction to Frames

14.1. Introduction to Frames

Frames allow authors to display several HTML documents in the browser window at one time, each in its own scrollable subwindow. Introduced by Netscape Navigator 2.0, frame support was soon added by other popular browsers. The HTML 4.01 and XHTML 1.0 Recommendations include a Frameset DTD for framed documents. XHTML 1.1 omits all frame elements.

Framed documents are typically used as a navigation device in which all of the navigation options stay put in one frame while the linked content documents are displayed in another frame. Because frames may include scrollbars and scroll independently of one another, frames are a method for making sure one page component stays put on the page while the rest of the page is free to scroll.

It is important to note that frame-like functionality (in which one element stays fixed and the rest of the page scrolls) can also be accomplished with CSS using the position: fixed property. Unfortunately, Internet Explorer 6 for Windows and earlier do not support fixed positioning , but there are workarounds as noted in Chapter 25.

Due to reliable browser support, frames are still an option for navigation and other uses. However, they do present certain problems and peculiarities that have led to their currently controversial status. 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 or your clients' needs.

14.1.1. Advantages

Consider these advantages to using frames:

• 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 element, you can add alternative content for browsers that do not support frames. This accessibility feature is built into the frames system.

14.1.2. Disadvantages

Also keep in mind these disadvantages:

• 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.

• 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.

• Multiple documents for each web page makes the site more difficult to manage and update.

• 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.

• It is more difficult to track actual page (or ad) impressions when the pages are part of a framed document.

With the pros and cons in mind, take a look at how framed documents are constructed.