setIdAttributeNode method

If the parameter isId is true, this method declares the specified attribute to be a user-determined ID attribute. This affects the value of Attr.isId and the behavior of Document.getElementById, but does not change any schema that may be in use, in particular this does not affect the Attr.schemaTypeInfo of the specified Attr node. Use the value false for the parameter isId to undeclare an attribute for being a user-determined ID attribute.

setIdAttributeNode(idAttr, isId)
Parameters	AttridAttr The attribute node. booleanisId Whether the attribute is a of type ID.
Returns	void
Throws	DOMException NO_MODIFICATION_ALLOWED_ERR: Raised if this node is readonly. NOT_FOUND_ERR: Raised if the specified node is not an attribute of this element.