Today I came across small “feature” that took me few minutes to realize, what is happening.
I am using IE 11 to debug older ASP.NET WebForms app (with older I mean we are just now moving away from HTC files – Microsoft specific stuff).
IE is loading page from my local IIS with x-ua-compatible flag like described on the link provided, setting rendering core to use version 8 so behaving like IE8.
Loading my page like this results to loading just some .htc files referenced. If I set breakpoint to some code in .htc file, it will be not hit, even some objects are declared as undefined but strangely executing any method over these yields results and works as expected (so I suppose the JS core works as it should , it’s just matter of developer tools).
Quick fix to this is : just reload the page, then all files will be loaded and you can happily work as expected.
Small sample how it looks like in IE developer tools (the very same page, just loaded 2 times) :
Just in the case, version of my IE 11 :
Hope this helps someone, enjoy.