Lookup Lists: Introduction - Doc JavaScript

Lookup Lists

This week's column explains how to create a lookup list. A lookup list is a menu that enables you to enter the first few characters of a desired option, and the nearest match is instantly selected. Windows 95, for example, features a lookup list in the Help window of almost every program, under the Index tab. Our example list includes many different web sites:

Note that if you are running the Macintosh version of Navigator 4.0x, the script displays a standard list. We'll explain this later in the column.

Give it a try by entering "cos" (without the quotes) one character at a time. Then delete the characters one at a time. Notice that the selection changes according to the text in the box.

If you're using Navigator 4.0x, you probably noticed a limitation. When the script selects an option far down the list (one that isn't visible at first), the menu doesn't automatically scroll down to show the selected option. Since Navigator 4.0x doesn't feature a method to scroll select menus, there is no workaround for this problem. We'll have to live with it. In this column you'll learn:

1. How to define the basic global variables for the script.
2. How to initialize the lookup list.
3. How to print the list's HTML code via JavaScript.
4. How to update the text field when the user manually changes the selection.
5. How to select a matching option.

For your convenience, you may also view the entire code.