Professional JavaScript | 37 | WebReference

Professional JavaScript | 37

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Professional JavaScript


WebTV is the best known and first visible set-top Web browser. Just like the major browsers, you get an email client as well as HTML. Supposedly with over a million users, WebTV is obviously quite popular. You can have a look at their site here:

The JavaScript support in WebTV is about at the Netscape 3.0 level. For HTML authors and script developers, the company provides set-top box emulation software that you can download and run for free on your Web browser. This is just a browser that acts exactly like the set-top browser. The sole exception is that the emulator displays pages more clearly because the computer screen is better than the TV tube. Here is a picture of the main window:


In the real set-top browser, there are no menus, window borders or toolbars - all you get to work with is the area inside the inner window named "Browser Window". This inner window can't be resized. The bright box around "Arts and Humanities" is what a hypertext link looks like - a single underline is too hard to see on a TV.

The second window of this browser looks like this:

This is the remote control that a real user has in their hand. By clicking the direction arrows, the user can move the bright box from link to link.

What does it all mean for JavaScript? Your JavaScript enhanced page may work on WebTV if you use only basic Netscape 3.0 features of the language and object model. The set-top box can't handle floating point numbers in JavaScript, and it can't open extra windows, so no alert() or - these are described in later chapters. The WebTV Website has some documentation on what's in and what's out.

What the set-top box loses in compatibility it gains in its own fancy enhancements. Specifically, it has a markup language in addition to HTML called TVML. Between TVML, HTML and JavaScript, you can integrate live TV channels and static Web pages together for some very fancy audio-visual results that are still difficult to achieve smoothly on a personal computer.

Finally, here's a screenshot of a great Web site that looks lousy on WebTV:


This is a very crowded page for a low-resolution TV screen. The images down the left-hand and right-hand sides of the pages would be unreadable, because of their tiny text. Although they're advertising, a reader of this site would likely want to follow those images to explore their contents. Remember this is a picture of the emulator, not the real thing, and so is also artificially clear. At least the site designer hasn't elected to use fancy fonts, which would be completely lost in the set-top browser. Note the bright squares in the top right hand corner - the user would have to navigate with the remote control some distance before any of the news items' links could be reached. Great site, and it's fortunate that WebTV isn't hugely popular.

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Created: April 12, 2001
Revised: April 12, 2001