Find out if an attribute is the element's ID attribute or not:
The result of x could be:
The isId property returns true if the attribute is of type ID, otherwise it returns false.
This property is read-only.
|isId||Not supported||Not supported||Not supported||Not supported||Not supported|
Note: This property was supported in Chrome, Firefox and Safari 5+, but support has been removed.
|Return Value:||A Boolean, returns true if the attribute is of type ID, otherwise false|
|DOM Version||Core Level 3|