CSSStyleSheet: addRule() method
Deprecated
Avoid using this feature in new projects. This feature may be a candidate for removal from web standards or browsers.
The obsolete CSSStyleSheet interface's
addRule() legacy method adds a new rule to the
stylesheet. You should avoid using this method, and should instead use the more standard
insertRule() method.
Syntax
addRule(selector, styleBlock, index)
Parameters
selector-
A string specifying the selector portion of the CSS rule. The default is the string
undefined. styleBlock-
A string indicating the style block to apply to elements matching the
selector. The default is the stringundefined. indexOptional-
An optional index into the stylesheet's
CSSRuleListat which to insert the new rule. Ifindexis not specified, the next index after the last item currently in the list is used (that is, the value ofcssStyleSheet.cssRules.length).
Return value
Always returns -1.
Note that due to somewhat esoteric rules about where you can legally insert rules,
it's possible that an exception may be thrown. See insertRule() for more information.
Usage notes
This method is implemented by browsers by constructing a string using the template
literal `${selector}{${styleBlock}}`, then passing it into the standard
insertRule() method.
Therefore, given existing code such as the following:
cssStyleSheet.addRule(selector, styles, 0);
You can rewrite this to use the more standard insertRule() like this:
cssStyleSheet.insertRule(`${selector} {${styles}}`, 0);
Specifications
| Specification |
|---|
| CSS Object Model (CSSOM) # dom-cssstylesheet-addrule |