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Drop obsolete browser support #3208
Description
With the recent release of React 16, React is beginning to depend on more browser features such as Map, Set, and requestAnimationFrame.
This issue proposes dropping support for IE9 and IE10, as they had reached End-of-Life on January 12, 2016.
IE 11 has basic support for Map and Set, enough for React to function:
IE 11 also has support for requestAnimationFrame and cancelAnimationFrame.
fetch is not supported in any version of Internet Explorer, nor is Object.assign() or Promise, so all existing polyfills would have to remain.
This will prevent us from having to add about ~6kb in polyfills, and has the added benefit of increasing our syntax support level to that of IE 11.
This allows users to use let, const, and block level function declarations [in depended upon packages]!
Activity
Timer commentedon Sep 28, 2017
Additionally, we may leave the syntax level IE 9 (
vareverything), and then provide an additional polyfill for users who still want IE9 support (includingMap,Set,requestAnimationFrame, andcancelAnimationFrame).oriSomething commentedon Sep 28, 2017
@Timer Maybe splitting to 2 builds by using
nomodulefeature for the newer browsers?andriijas commentedon Oct 2, 2017
Very welcome. However I suggest to not to create ie9 polyfill. By letting the very small amount of people using obsolete browsers, giving them life jackets to continue doing so will lessen the chances of them upgrading to a more secure version of their current browser.
gaearon commentedon Jan 8, 2018
We ended up not doing anything—people opted into dropping those browsers by updating to React 16. Those who didn't want to could add polyfills themselves.