Sets or gets the MIME type of the media object referenced by the SRC attribute.
object.type = sType sType = object.type
the MIME type of the media associated with the element.
By default, the server should send the MIME type to the user agent. If that mechanism fails, the MIME type is obtained from this property.
This property cannot be modified in script after the onload event fires on the document body.
- Introduction to HTML+TIME