Dynamic Styles: A Brief History
A Brief History
The introduction of Cascading Style Sheets (CSS) in versions 3.0 of both Internet Explorer and Netscape Navigator revolutionized the way Web authors wrote their pages. CSS allows authors to do work differently. First, instead of mixing content and style in one document, authors can now separate between content and its formatting instructions which go into the style sheet. Secondly, authors do not have to repeat formatting instructions for every instance of the same element type, because CSS allows them to specify styles for generic types.
style) which is in itself an object. The
style object's properties include all the style attributes such as colors, fonts, spacing, indentation, position, and text's visibility. To change the appearance of an element on the page, you simply change the corresponding property of the
style object. You may also change a direct attribute of an HTML element. For example, you can switch the image of an
IMG element, by setting its
SRC attribute to a different GIF file.
Internet Explorer 5 and later supports dynamic properties, which allow Web authors to assign elements, properties, and formulas to DHTML properties. Dynamic properties are set by the
setExpression() method. You can force recalculation of all expressions by calling the
recalc() method. Learn more about dynamic properties in Column 65, Dynamic Properties. Sometimes, you want to be notified when a dynamic property changes. Elements fire the
propertyChange event (handled by the
onPropertyChange() event handler) when either an object, an
expando, or an object's style changes. (
expando is a property of the
document object and it can be either retrieved or set. When set to
true, new properties can be added to objects. When set to
false, no new properties can be added to objects.) Use the
onPropertyChange() event handler and the
currentStyle object to respond to changes throughout a document.
How to change the color
Produced by Yehuda Shiran and Tomer Shiran
Created: August 14, 2000
Revised: August 14, 2000