So as a lot of you prob know Microsoft has pushed IE 10 in a KB release on Apr 9th. For some of us this has caused a headache because there is a issue with how the
<meta http-equiv="X-UA-Compatible" content="IE=8" />
tag is interpreted and we use this as developers sometimes for SharePoint, Dynamics CRM, and using some older libs in web apps for certain pages. Now the answer for us was removing this tag as it was for code I rewrote long ago. But lets get to the underlying cause. so if you make a demo page and place this tag in the meta, then put two text boxes and attach js validate 1.1 to the boxes and make one required and one not. When you submit the page you will see both will show up as required. So lets hit F12 and see whats up with the rendering.
So as you see in the screen cap above IE 10 is getting the Doc Mode correct but not the Browser Mode. This is great for those who have been pushing Microsoft for proper web standards but man they could have put out some warning instead of putting IE 10 in a KB so it would have been more apparent when skimming over upcoming WSUS that IE 10 was coming. This causes issues in rendering as the doc type clashes with the browser mode in how the page is processed/handled by IE breaking quite a few JS libs.
If you are experiencing these issues you can either remove the tag if it is not needed, detect the browser and display a warning, or look at your code and fix the issues that are holding it back from IE 10. In the short term you also can do the following.
1. Use a loose instead of strict doctype
2. Validate your markup and make sure it is correct
3. Add a site to compatibility mode view settings
4. change tag to
<meta http-equiv="X-UA-Compatible" content="IE=EmulateIE8" >
If that does not work you may have a long road ahead. Stay strong my friends and till next Microsoft update don’t let your code have a meltdown.