unsigned long insertRule(String rule, unsigned long index) throws DOMException;
rule
The complete, parseable CSS string representation of the rule to be added.
index
The position at which the new rule is to be inserted into the cssRules array, or the cssRules.length to append the new rule at the end of the array.
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 position.
INDEX_SIZE_ERR
index is negative or greater than cssRules.length.
NO_MODIFICATION_ALLOWED_ERR
This @media rule and its cssRules array are read-only.
SYNTAX_ERR
The specified rule contains a syntax error.
This method inserts the specified rule into the cssRules array at the specified index.