What is the meaning of polyfills in HTML5?

javascript html fallback polyfills shim
Jitendra Vyas picture Jitendra Vyas · Aug 17, 2011 · Viewed 149.2k times · Source

What is the meaning of polyfills in HTML5? I saw this word in many sites about HTML5, e.g. HTML5-Cross-Browser-Polyfills.

So here we're collecting all the shims, fallbacks, and polyfills in order to implant HTML5 functionality in browsers that don't natively support them.

I actually don't understood what is the meaning of polyfills.

Is it a new HTML5 technique or a JavaScript library? I never heard this word before HTML5.

And what is the difference between shims, fallbacks, and polyfills?

Answer

Calvin Froedge picture Calvin Froedge · Aug 17, 2011

A polyfill is a browser fallback, made in JavaScript, that allows functionality you expect to work in modern browsers to work in older browsers, e.g., to support canvas (an HTML5 feature) in older browsers.

It's sort of an HTML5 technique, since it is used in conjunction with HTML5, but it's not part of HTML5, and you can have polyfills without having HTML5 (for example, to support CSS3 techniques you want).

Here's a good post:

http://remysharp.com/2010/10/08/what-is-a-polyfill/

Here's a comprehensive list of Polyfills and Shims:

https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-browser-Polyfills

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