HTMLObjectElement - Web APIs
htmlobjectelement.codetype is a domstring that reflects the codetype html attribute, specifying the content type of the data.
... the following properties are now obsolete: align, archive, border, code, codebase, codetype, declare, hspace, standby, and vspace.

<object> - HTML: Hypertext Markup Language
codetypehtml 4 onlyobsolete since html5 the content type of the data specified by classid.