[bug] IE11 needs Object.keys for ES6 behavior

[agriffis]

What

polyfill.io doesn't return polyfill Object.keys on IE11 by default, because it has an implementation. But the native implementation is the ES5 variant which breaks various libs, for example see reduxjs/redux-toolkit#152

Details

The Object.keys polyfill supports ES6 behavior:

polyfillpolyfill/polyfill-service#991
polyfillpolyfill/polyfill-service#1033

but it's not included in the bundle for IE11

The script tag I'm using is

<script src="https://polyfill.io/v3/polyfill.js?features=default,es5,es6,es7,es2017,console.debug,console.log,console.warn,fetch,HTMLPictureElement,Symbol|Gated"></script>

[agriffis]

Actually the problem might be that polyfill.io isn't returning the Object.keys polyfill for IE11

[agriffis]

Here's a bit more...

https://polyfill.io/v3/polyfill.js?features=Object.keys&ua=Mozilla%2F5.0+%28compatible%3B+MSIE+10.0%3B+Windows+NT+6.1%3B+WOW64%3B+Trident%2F6.0%29 sends the polyfill. That's using the IE 10 user-agent: Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.1; WOW64; Trident/6.0)

https://polyfill.io/v3/polyfill.js?features=Object.keys&ua=Mozilla%2F5.0+%28Windows+NT+10.0%3B+WOW64%3B+Trident%2F7.0%3B+rv%3A11.0%29+like+Gecko does not send the polyfill. That's using the IE 11 user-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko

which is weird because the config shows it should apply to all IE versions:

https://github.com/Financial-Times/polyfill-library/blob/master/polyfills/Object/keys/config.toml#L18

[agriffis]

Well sheesh, this has already been fixed in 1b237fb

It's just not serving from polyfill.io yet

[JakeChampion]

this is now live :-)

[agriffis]

Thanks Jake!

Unfortunately, though, fixing this just reveals that the polyfill for Object.getOwnPropertyNames isn't ES6 compliant either. I'll file a separate issue.

[agriffis]

Looks like there's already an issue #218