var object = object.addRule(Selector, Style, Index);
String that specifies the selector for the new rule. Single contextual selectors are valid. For example, "div p b" is a valid contextual selector.
String that specifies the style assignments for this style rule. This style takes the same form as an inline style specification. For example, "
color:blue" is a valid style parameter.
Integer that specifies the zero-based position in the rules collection where the new style rule should be placed. Default is -1, which specifies that the rule is added to the end of the collection.
Returns an object of type
Reserved. Always returns -1.
This example uses the addRule method to add a rule that sets all bold text appearing in a DIV to the color blue.
<STYLE> </STYLE> <DIV> Internet Explorer makes <B>HTML</B> dynamic. </DIV> <SCRIPT> var new_rule; new_rule = document.styleSheets.addRule("DIV B", "color:blue", 0); </SCRIPT>
You can add up to 4095 style rules with the addRule method. After that, the method returns an “Invalid Argument” exception. You can apply rules to a disabled styleSheet, but they do not apply to the document until you enable the styleSheet.
Microsoft Developer Network: [Windows Internet Explorer API reference Article]