The current mime.types file has an entry application/x-javascript js Use of such media types is discouraged per RFC 2048, section 2.1.4; the IESG- approved media type application/javascript should be used instead (see https://datatracker.ietf.org/public/pidtracker.cgi?command=view_id&dTag=7686 for details).
RFC 4329 "Scripting Media Types" now is published since April 2006. See ftp://ftp.rfc-editor.org/in-notes/rfc4329.txt for details. Text Media-Types http://www.iana.org/assignments/media-types/text/ Application Media-Types http://www.iana.org/assignments/media-types/application/
See also: Bug 40299 "ECMAScript and JavaScript media types in mime.types file" with patch: http://issues.apache.org/bugzilla/show_bug.cgi?id=40299
When does this bug get fixed in Apache? All major browser vendors (except Microsoft) did do their homework and did adjust the new MIMEType for JavaScript/ECMAScript.
Fixed in all versions.