unsigned long insertRule(String rule, unsigned long index) throws DOMException;
rule
The complete, parseable text representation of the rule to be added to the style sheet. For style rules, this includes both the element selector and the style information.
index
The position in the cssRules array at which the rule is to be inserted or appended.
The value of the index argument.
This method throws a DOMException with one of the following code values in the following circumstances:
HIERARCHY_REQUEST_ERR
CSS syntax does not allow the specified rule at the specified location.
INDEX_SIZE_ERR
index is negative or greater then cssRules.length.
NO_MODIFICATION_ALLOWED_ERR
The style sheet is read-only.
SYNTAX_ERR
The specified rule text contains a syntax error.
This method inserts (or appends) a new CSS rule at the specified index of the cssRules array of this style sheet.