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Browser-tailored polyfills

Oct 2020
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Polyfills are extremely useful to help the web evolve, providing substitute implementations of modern features for browsers that don't implement them (yet). Too often, though, web applications ship polyfills to browsers that don't need them, which causes unnecessary download and parsing overhead. The situation is becoming more pronounced now as only a few rendering engines remain and the bulk of the polyfills target only one of them: the Trident renderer in IE11. Further, market share of IE11 is dwindling with support ending in less than a year. We therefore suggest that you make use of browser-tailored polyfills, shipping only necessary polyfills to a given browser. This technique can even be implemented as a service with Polyfill.io.