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Re: XHR LC comments

From: Laurens Holst <lholst@students.cs.uu.nl>
Date: Thu, 15 May 2008 20:57:44 +0200
Message-ID: <482C87A8.30106@students.cs.uu.nl>
To: Julian Reschke <julian.reschke@gmx.de>
CC: Anne van Kesteren <annevk@opera.com>, public-webapi@w3.org
Julian Reschke schreef:
> Sorry, was reading one thing, but thinking about something else.
>
> Thinking of it, could you please add a clarification that setting to 
> an empty string is legal, and MUST NOT be ignored? I recall that 
> Microsoft's original XHR (ActiveX) implementation got that wrong, not 
> setting the header at all.

When invoking request.setRequestHeader('Accept', ''):

- Firefox 3b5 removes the Accept header
- Internet Explorer 8 (in IE7 mode) sends Accept: */*
- Safari 3.1.1 sends Accept:
- Opera 9.24 sends Accept: text/html, application/xml;q=0.9, 
application/xhtml+xml, image/png, image/jpeg, image/gif, 
image/x-xbitmap, */*;q=0.1

When invoking request.setRequestHeader('Accept', null):

- Firefox 3b5 removes the Accept header
- Internet Explorer 8 (in IE7 mode) sends Accept: null
- Safari 3.1.1 sends Accept: null
- Opera 9.24 sends Accept: text/html, application/xml;q=0.9, 
application/xhtml+xml, image/png, image/jpeg, image/gif, 
image/x-xbitmap, */*;q=0.1

So it is clear that here, too, browsers are in great disagreement. I am 
not sure what the correct approach here is, though '' meaning setting 
“Accept” and null meaning removal of the header sounds sensible.

Note by the way that Opera always prepends the set Accept header to its 
default value, resulting in e.g. Accept: */*, text/html, 
application/xml;q=0.9, application/xhtml+xml, image/png, image/jpeg, 
image/gif, image/x-xbitmap, */*;q=0.1 when invoking 
request.setRequestHeader('Accept', null);

I can’t believe how horribly broken this all is. No wonder few people 
depend on this header. Fortunately, as a result it can also be fixed 
without breaking much.

I’ve also posted these results at http://www.grauw.nl/blog/entry/470 , 
the page source contains a test case.


~Grauw

-- 
Ushiko-san! Kimi wa doushite, Ushiko-san nan da!!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Laurens Holst, student, university of Utrecht, the Netherlands.
Website: www.grauw.nl. Backbase employee; www.backbase.com.




Received on Thursday, 15 May 2008 18:59:18 GMT

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