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HTTP Doctype header issue causes problems in IE7?

Answer 1

+2 A:

Depends on how it is broken. JS doesn't care about the DOCTYPE, but the HTML of the widget might. There are differences but it's far more likely that the problem is quirks mode vs standards mode.

Here is a chart of which DOCTYPEs trigger which modes in various browsers

Rob 2010-09-30 17:57:07

Precisely, the doctype can trigger quirks or standard mode. http://en.wikipedia.org/wiki/Quirks_mode

Savageman 2010-09-30 18:26:15

I believe that either DOCTYPE should trigger standards mode, and then the page is probably breaking standards

Rob 2010-09-30 18:35:24

JS **does** care about quirks/standards mode, and HTML 4.01 Transitional with no URI triggers quirks mode.

David Dorward 2010-09-30 18:57:25

In what way does JS care about quirks vs standards mode? To JS it is all parsed DOM.

Rob 2010-09-30 19:09:03

Different bugs are exposed in the JS DOM API depending on mode. (I wouldn't be surprised if there were core JS differences too, but I don't know of any off the top of my head)

David Dorward 2010-09-30 19:19:30

The changes are to DOM and rendering, not JS. The JS engine is the same. http://stackoverflow.com/questions/1503843/quirksmode-javascript-implementation

Rob 2010-09-30 19:39:10

Switching `setAttribute` between broken and standard has nothing to do with rendering, not does the change in `getElementById('foo')` returning `<a name='foo'>...</a>`.

David Dorward 2010-09-30 19:49:08

@Rob- looks like the second header was triggering quirks mode. Thank you for the chart- very helpful.

Yarin 2010-09-30 20:18:32

Answer 2

A:

IE has been a huge culprit for having problems when doctypes arent set properly or arent showing up properly. I havent seen ie 7 doing it that often, but i know IE 6 was terrible. Are you able to declare what the doctype is?

Ascherer 2010-09-30 18:51:22

We can't touch the doctype as it is the client's site, and we are just delivering a widget. Thanks.

Yarin 2010-09-30 20:21:34

Answer 3

+1 A:

The second doctype will trigger Quirks mode in IE. In this mode it emulates a number of bugs from IE 5.x so that it can be compatible with 199x era websites.

This has a wide range of effects and includes such things as getting the meaning of width in CSS wrong (fixed from IE6 onwards but only in standards mode) and getting setAttribute wrong (fixed from IE8 onwards, but only in standards mode).

David Dorward 2010-09-30 18:56:38

This seems to be it. The specific issue ended up being that an absolutely positioned div with style="left:0px;right:0px" ended up collapsing to nothing, and the fix was to specify an explicit width.

Yarin 2010-09-30 20:20:40

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HTTP Doctype header issue causes problems in IE7?

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