Scrolling HTML Basics, Part I: Netscape Version - Doc JavaScript

Scrolling HTML Basics, Part I: Netscape Version

[29] DOCJSLIB Version 3.0: Page Watermarks [28] DOCJSLIB Version 2.0 [27] DOCJSLIB Library, Part I [26] JavaScript 1.3 Review, Part II [25] JavaScript 1.3 Review, Part I [24] Internet Explorer 5.0 Review, Part III

This column is a first in a series that explains you how to write scrolling HTML. Scrolling HTML is an efficient way to display more information in a given area than a static HTML would. As you have probably noticed from your Web surfing, scrolling HTML (a scroll box) is often used in displaying up-to-the-minute headlines, sports event scores, and weather information across the US. The most popular scroller is perhaps the CNN's NYSE ticker. A TV viewer can get a glimpse of all NYSE values through a single scrolling line across the TV monitor.

In this column we show you how to implement scrolling HTML in Netscape Navigator. The code is mostly straightforward, but gets tricky at times, due to some bugs (or are they features?) in Netscape Navigator. Since there is a lot of code and new ideas to present and explains about this scrolling HTML, we thought it would be a better idea to split the subject between a few consecutive columns. You are probably curious as to when is DOCJSLIB 4.0 due? Our plan is to release it at the end of this Scrolling HTML series, when we'll add the new code to DOCJSLIB. Keeping this end in mind, we have packaged the scrolling HTML code with an API-like interface. In upcoming columns we'll enrich this interface with Internet Explorer support, as well as with new scroll box features.

In this column you'll learn:

• How to devise a scrolling algorithm.
• How to use the Netscape Navigator's Layer object.
• How to position a layer within another layer.
• How to scroll the box.
• How to stop the box and release it with the mouse.
• How to workaround Netscape Navigator's problems.
• How to prepare the input file (feed).
• How to position a scroll box.

At this point, you may also view the code for the Scroll Box, as well as download its zipped version.