Recently I have come across a question about the HTML5 feature support by different browsers. How you make sure that the application render properly in non-supporting browsers?
Answer for above question is the proper usage of Modernizr and Polyfilling.
Polifill is a code block that mimics the functionality of an API by providing fallback functionality to older browsers. For example, LocalStorage introduced in HTML5 is not supported in IE7; but we can use a Polifill to implement the LocalStorage support in IE7.
Modernizr along with Polyfill help the UI developer to address the non-supporting browsers.