developing with IE9 in mind

Question

I'm curious if there are any specific things that I should be aware of as a developer with IE9, there's no question that Microsoft um... "forgot" to add compatibility for things like web-sockets etc. But in terms of CSS, font rendering, and JavaScript what precautions do I need to take?

Answer 1

Unless you are specifically developing for IE9 (like in the case of a corporate client that typically are early adopters), I wouldn't consider IE9 at all unless you want to alienate the 50% of internet users who will likely still utilize IE8 or earlier as of early 2012.

Answer 2

Ok, all these answers are wrong :)

1) You have to support IE9 now. People are going to be visiting your site/app using IE9, and its officially out. This will only become more prevalent.

2) IE9 does not render exactly like IE8, and it doesn't just render 'better', either. (It does render a heck of a lot faster though). So that means, your site/app will probably be broken in IE9. So that means: another browser to test.

So you have to consider IE9 now, and there's no sitting back.

Answer 3

These pages contains a lot of stuff you may expect in IE9:

• Internet Explorer 9 Guide for Developers
• Internet Explorer 9 Compatibility Cookbook

Answer 4

First things you should know:

1. It passes 95% on Acid3 tests, while still in Beta
2. Its fast JScript Chakra engine conforms to ECMA-262 5th Edition Standard 100%
3. It is HTML5 Ready.

And it is fast in rendering, exceeding 60fps on Canvas Animation at 1920x1080 px frame resolution on my desktop. Web Open Font Format supported too http://msdn.microsoft.com/en-us/ie/ff468705.aspx

Answer 5

I don't think you should do anything special for anything, except enjoy the breath of fresh air you'll get because your sites will suddenly start to behave (closer to) normally when visited by IE users.

The only thing you'll need to do: write less workarounds than before.

I'd say just kick back and relax.

For specific things, refer to Lekensteyn's answer's link.

Answer 6

Microsoft have failed to mention one major thing... their change from using GDI rendering to DirectDraw.

This can cause serious blurry text on sites, and you might not even be aware of it (depending on the client setting etc).

Important information regarding fonts, blurriness and rendering in IE9

• IE 9 does not use sub-pixel antialiasing under certain conditions

MSDN sources:

• Sub-pixel Fonts in IE9 - blogs.msdn.com/b/ie/archive/2010/11/03/sub-pixel-fonts-in-ie9.aspx
• IE9's blurry font text - www.hanselman.com/blog/TheUltimateGuideOfFiveThingsForNewIE9UsersWhoFearChange.aspx

Answer 7

I agree with mtyson. Get started on checking your site in IE9 now. I manage many sites for a client and we are noticing a lot of problems in IE9. While it works fine in FF/Chrome/IE8 it is sometimes not displaying elements on the screen at all. Of course you can hit the compatibility mode, but to me that's not a solution. I am making sure our developers are aware of all problems in 9 now rather than next year when more people are using it and the sites are broken.