Why does IE9 switch to compatibility mode on my website?
Works in IE9 documentMode for me.
Without a X-UA-Compatible header/meta to set an explicit documentMode, you'll get a mode based on:
- whether the user has clicked the ‘compatibility view’ button in that domain before;
- perhaps also whether this has happened automatically due to some other content on the site causing IE8/9's renderer to crash and fall back to the old renderer;
- whether the user has opted to put all sites in compatibility view by default;
- whether IE thinks the site is on your intranet and so defaults to compatibility view;
- whether the site in question is in Microsoft's own list of websites that require compatibility view.
You can change these settings from ‘Tools -> Compatibility view settings’ from the IE menu. Of course that menu is now sneakily hidden, so you won't see it until you press Alt.
As a site author, if you're confident that your site complies to standards (renders well in other browsers, and uses feature-sniffing to decide what browser workarounds to use), I suggest using:
<meta http-equiv="X-UA-Compatible" content="IE=Edge"/>
or the HTTP header:
X-UA-Compatible: IE=Edge
to get the latest renderer whatever IE version is in use.
I put
<meta http-equiv="X-UA-Compatible" content="IE=Edge"/>
first thing after
<head>
(I read it somewhere, I can't recall)
I could not believe it did work!!
To force IE to render in IE9 standards mode you should use
<meta http-equiv="X-UA-Compatible" content="IE=edge">
Some conditions may cause IE9 to jump down into the compatibility modes. By default this can occur on intranet sites.