01. Valid Doctype
Ensure that you're using a doctype that recognizes modern web standards like HTML5 & CSS3:
02. UA Sniffing
Instead of UA sniffing, future-proof your site by implementing feature detection to make it easier to support new browser versions.
03. Vendor Prefixes
Ensure that vendor prefixes for all major browsers are included in your CSS. This allows you to offer a consistent experience in all modern browsers At the very least, ensure that the non-prefixed version of a CSS property is specified.
04. Browser Specific CSS Hacks
If you're using CSS browser hacks, there is an assumption that the functionality will be available going forward. As new browser versions come out, many of those hacks aren't necessary and in many cases, will be deprecated.
05. Use the Latest Frameworks & Libraries
JavaScript libraries and CSS frameworks are constantly updated to ensure proper compatibility with browsers If you're using a version that's very dated, you may find that as browsers are updated, the old code may not work as expected. Stay current when possible.
06. Conditional Comments
Conditional comments can be useful but as of Eio, they're no longer supported. If your code is dependent on them (e.g.: serving up different stylesheets), you're going to have to rethink the approach and ensure you're focusing on standards.
07. Focus on Stable Standards
With IE9, Microsoft made a concerted effort to focus on standards-based features and as of IE10, several non-standard features like DX Filters were deprecated. Use the IE Compat Inspector to check your site for problems and solutions.
