[whatwg] <meta http-equiv="X-UA-Compatible" content="IE=edge" />

Christoph Päper christoph.paeper at crissov.de
Tue Jan 22 17:28:02 PST 2008

Brenton Strine:
> (...) IE8 'passes' the Acid2 test, but (...) won't render pages  
> with the new standards-compatibility unless you explicitly tell it  
> to with this meta tag:
> <meta http-equiv="X-UA-Compatible" content="IE=edge" />
Note that 'edge' is actually discouraged and authors should instead  
provide version numbers they successfully tested their documents in.  
(The list may get rather long and incomplete over time, but the QA  
department can finally show off.)

If I saw the need for even more rendering mode switching, I would  
develop a fuzzy algorithm taking cache lifetime, resource generation  
or modification and UA deployment dates into account. This then could  
be amended (i.e. overridden) with meta data providing a date on which  
rendering was (virtually) certified with most recent versions of the  
browsers the author / owner wants to support. Quirks mode would use  
the youngest engine released before that date.

Or I would start in best standard-conforming mode and restart in the  
next quirkier mode on encountering the first "error". Iterate. May  
add delay or flicker, though.
> One of the reasons I write standards-compatible code is so that my  
> websites will work in future browsers when they support new/better  
> features. All such webpages are effectively locked into IE7 now,  
> and won't get any benefits of the newer browsers unless I add this  
> new meta tag.
Yes, Microsoft usually rewards the lazy and sloppy ones (even for the  
prize of punishing the avid and accurate ones). It's part of their  
success, hence it's unlikely to change.

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