The rules that are used to construct a style are comprised of multiple expressions. You can use this method to assign a new value to an expression within a style item with that value being generated by a callback to a script function.

The rule might contain a line such as:

width:200px

The setExpression() method can be applied to the style object containing the rule with that expression like this:

myStyle.setExpression("width:", "callBack()", "JavaScript")

The value of the width parameter would be defined by the result of calling the callBack() function in the JavaScript context.

The language argument can be one of the following:

• JavaScript

• JScript

• VBScript