MIME Media Type for ECMAScript

[Robert Orosz <roboro@auto-trol.com>]

All,

During the development of WebCGM 2.0, I pointed out in one of my review
assignments [1], that the Internet Assigned Numbers Authority (IANA)
deprecated "text/ecmascript" as the media type for ECMAScript scripts.
Actually, IANA used stronger language than "deprecate," they called it
"obsolete" [2]. This impacts WebCGM because the HTML script element has a
required type attribute. The value of this attribute is the IANA registered
media type (or content type as the HTML specification calls it) for the
scripting language used in the contents of the script element. However, we
subsequently discovered that Internet Explorer (IE), which was at release
6.0 at the time, failed to execute scripts if the type attribute of the
script element was set to "application/ecmascript" instead of
"text/ecmascript" [3]. Since all of our implementers were targeting IE, we
had no choice but to use the "obsolete" text/ecmascript media type in the
specification text and in the test suite. By the way, the example in section
3.4 of the current WebCGM 2.1 Editor's Draft, still uses
"application/ecmascript" as the value of the type attribute of the script
element. This change was triggered by my review [1], and we should probably
revert that back to "text/ecmascript" as well in order to be consistent with
the rest of the document.

It retrospect, the failure of IE 6 to recognize application/ecmascript as
the media type for ECMAScript is not surprising since IE 6 was released some
five years prior to the publication of RFC 4329, which establishes
application/ecmascript as the proper media type for ECMAScript [4]. However,
with the subsequent release of IE 7 and especially IE 8 with its claim of
being "more standards-compliant," I decided to revisit this issue.

Rather than trying to execute a test from the test suite, which would
require a WebCGM plugin on every machine I wanted to test, I created a
simple HTML page with a script that executes when the page is loaded. The
type attribute of the script element is set to "application/ecmascript" and
the script simply modifies the last two elements in the HTML to state that
the test passed. I've attached the HTML file to this message if anyone else
wants to try it.

IE 7 and IE 8 (as well as IE 6 of course) fail the test. Every other browser
that I tried passed it. I'm a little surprised about IE 8 failing this test.
Perhaps I am missing something. Does anyone know of a setting that enables
IE 7 or 8 to recognize the application/ecmascript media type? I'd be curious
to know what others think about this issue.

Regards,

Rob

Rob Orosz
Senior Software Engineer
Auto-trol Technology
11030 CirclePoint Road
Suite 450
Westminster, CO. 80020
(303) 252-2262
http://www.auto-trol.com

[1] http://lists.oasis-open.org/archives/cgmo-webcgm/200509/msg00139.html
[2] http://www.iana.org/assignments/media-types/text/
[3] http://lists.oasis-open.org/archives/cgmo-webcgm/200605/msg00092.html
[4] http://www.ietf.org/rfc/rfc4329.txt

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