What Can JavaScript Do?

JavaScript can make things happen when the user clicks on a button or hyperlink, or places the mouse over a hyperlinked item. This can make your pages more helpful to the user. Here are some examples:

Rollover
Status bar messages

Manipulate elements of the page

JavaScript provides a way to manipulate content on the page, e.g. change: images (without a rollover), backgrounds, and the location of images, text and text attributes (using DHTML). Unfortunately, not all parts of web page that you would like to access are available yet. As web browsers advance, more features will be. Here are some examples:

Change background color
Cycling images and hyperlinks
Randomly moving images (Netscape Only)
Scrolling text

Control aspects of the web browser

JavaScript provides some control over the web browser itself, e.g. you can define the look and size of windows and change the location of the page. Here are some examples:

Resize window
Move window
Remove Toolbars
Redirect user

Interact with Forms

JavaScript can prepare information in a form before it is processed by a CGI script on the server. It can also eliminate the need for CGI in some situations by reacting to information supplied by the user to perform basic tasks that don't require information to be stored. Here are some examples:

Automatically update text fields
Check for empty fields
Use pulldown menus for navigation

Perform calculations

JavaScript is a programming language. Many of the calculating features of traditional programming languages are available to you. Here is an example:

Calculator
RGB to Hex converter

JavaScript is, of course, not limited to the categories that I have provided, but I hope that this give you a better sense of some of the things that JavaScript can do. Unfortunately, we are not going to learn how to do all of these examples, but by the end of this course you will have the framework to tackle these problems. (Remember: you can also examine the source code for these examples at any time.)