Persistent Data without CGI
This article about persistent data will be a little different from the first two. The first article, which covered javascript mouseovers, and the second, which covered frames, explored techniques that can easily be taken and applied to just about any website out there. In contrast, this article is a little more abstract, presenting a technique that, while extremely useful when needed, is not likely to be added to just any website.
Persistent data refers to information that “sticks around”. As a web coder, you probably came to accept the fact that each page of any site you design exists as a separate entity. That is to say, whatever you write on one web page, has no effect on the contents of any other. While this certainly simplifies the process of writing web pages, this fact often limits authors who want to take their designs one step further, by allowing the user to affect the web page he or she is about to see.
Both of the methods discussed here for creating persistent data require the use of javascript to some degree. This powerful, yet simple scripting language is the key to manipulating information without any help from the web server. As usual, everything will be explained from the ground up, but if you have a basic working knowledge of javascript, you will probably find this article much easier to follow. There are a few good resources listed at the end of the article that will give you a good overview of javascript and its capabilities.
It is assumed by this article that you have solid HTML skills. Specifically, the fundamentals of frames and forms will be relied upon heavily. Some places where you can quickly pick up the required knowledge are also listed at the end of this article.