text/javascript vs application/javascript

Question

I am curious about the semantics of the MIME types application/javascript versus text/javascript.

Obviously, one is supposed to be executed, and the other is supposed to be just text.

I see application/javascript when looking at headers of an external .js load.

HTTP/1.1 200 OK
Date: Mon, 13 Jan 2014 18:32:58 GMT
Server: Apache/2.2.22 (Unix) mod_ssl/2.2.22 OpenSSL/0.9.8e-fips-rhel5
Content-Type: application/javascript
Content-Length: 856
keep-alive: timeout=5, max=59
Via: 1.1 (jetty)
Accept-Ranges: bytes

If this application/javascript will execute the javascript, why don't we use

<script type="application/javascript">
  // some js code.
</script>

And vice-versa, why is an external js load not text/javascript?

Solution

Per this, text/javascript is obsolete. Use application/javascript instead.

text/javascript (Obsolete): JavaScript; Defined in and made obsolete in RFC 4329 in order to discourage its usage in favor of application/javascript. However, text/javascript is allowed in HTML 4 and 5 and, unlike application/javascript, has cross-browser support. The "type" attribute of the tag in HTML5 is optional and there is no need to use it at all since all browsers have always assumed the correct default (even in HTML 4 where it was required by the specification).

This standard is incompatible with IE<=8.