Return the id of the form containing the <input type="hidden"> element:
The result of x will be:
The form property returns a reference to the form containing the hidden input field.
This property returns a form object on success.
Note: This property is read only.
The form property is supported in all major browsers.
|Return Value:||A reference to the form element containing the hidden input field. If the hidden input field is not in a form, null is returned|