How good is the IE8 browser mode in Internet Explorer 10?

7
votes

I've started a new project that has to support Internet Explorer 8 and above. On my development machine I have IE 10. If I open the IE 10 developer tools (by pressing F12), I can change the mode to "IE 8", presumably emulating IE 8.

My question is: How good is that emulation? I see that Microsoft is kind enough to provide us with a virtual machine running IE 8 for testing, but it would certainly be more convenient if I could do the bulk of my testing using IE 10 in IE 8 compatibility mode.

Has anyone run into web sites that are rendered differently in actual IE 8 than they are in IE 10 in IE 8 mode? It would be very handy for me to see specific examples.

1
internet-explorerinternet-explorer-10ie8-compatibility-modeemulation
The IE team explicitly removed the browser emulation modes in IE11's F12 Developer Tools for the exact reason that they didn't want developers to be confused and think that using the F12 Tools compatibility modes was a replacement for testing in the actual browser version. - EricLaw
@EricLaw If having the various IE7 through IE10 browser modes in the Developer Tools is not intended to facilitate testing how sites will appear in those versions, what is the purpose of those modes? - Mark Meuer
As I recall, the primary reason was to enable a web developer to easily determine whether setting an X-UA-Compatible IE=EmulateIE* header would resolve problems for a given page. Since the IE team really wants to discourage that practice, this scenario now carries less weight for them. - EricLaw

1 Answers

7
votes

Having done a lot of compatibility testing for front ends of major websites, I can say it is no way a full substitute for using the actual browser version you want to test in. Whilst it's useful for seeing any immediate issues, we often found that those who relied on the dev tools in IE9 onwards were missing issues which were obvious in the full versions of IE7 and IE8.