JavaScript & DHTML Cookbook

Chapter 12. Visual Effects for Stationary Content

Introduction

The dynamic part of Dynamic HTML is not restricted to elements flying around the page, hierarchical menus popping up from the ether, and users dragging stuff around the page. An element that doesn’t move one pixel during its lifetime can still be dynamic because a change to one or more properties can alter the appearance of the element’s content. Such changes can be automatic or in response to user action.

Referencing Element Objects

If you intend to modify a characteristic of an element on the page, your script must be able to “talk” to the element. In the early days of client-side scripting, the browser exposed only a handful of elements as objects accessible to scripts. Those elements were generally the more interactive elements, such as form controls (buttons, text boxes, and the like). Syntax used to reference these elements followed a hierarchy of exposed elements, starting with the window object and then gradually narrowing the focus to the specific element. The window object is assumed for the current window, so references typically start with the document object. For example, if you assign a identifier to the name attribute of an a, form, or input element, references can employ those names:

document.linkName
document.formName
document.formName.controlName

When a document contains more than one type of exposed element, the group of elements of the same type can be referenced through an array (collection) ...