Polyfill

[ForbesLindesay]

Polyfilling via babel doesn't work very well in my experience since you don't normally run babel against node_modules. For apps (rather than libraries) I think it's generally best to just have global polyfills.

With this in mind, we could consider just adding a script to link to https://polyfill.io/v2/docs/ as the default polyfill. It provides a polyfill based on the user agent string so is a decent future proof default.

For non-polyfill babel-runtime components, we should do as @insin suggest in #51 (comment)

[gaearon]

Are any other major tools using/recommending this?

[ForbesLindesay]

Not that I'm aware of. Their usage stats seem fairly impressive (https://polyfill.io/v2/docs/usage). I'm not averse to us offering a different (e.g. static) js polyfill, I just think we should default to including a global polyfill of some sort.

The least controversial thing might be to just provide a static polyfill (not sure which ones are popular these days). I think we should provide something though as soon as possible.

[gaearon]

I would normally include core-js but it is way too large. I agree it’s better to ship a polyfill than not. I’ll ask for feedback on Twitter I guess.

[ForbesLindesay]

We could ship full core-js in development build, then build a custom core-js based on analysing code for which features are actually used in production. Doing that analysis in development would probably be way too slow since it would require analysing all of the dependencies.

We could also look at building a couple of different bundles, one for browsers with full ES5 support and another for browsers that need ES5 polyfills, then feature detect on the client.

[gaearon]

Feedback about polyfill.io seems generally positive.
I think we can get it in.
(Worst case: we’ll remove it later.)

[gaearon]

Do we have a good solution to this? polyfillpolyfill/polyfill-service#561

[apaleslimghost]

@gaearon we're fixing that soon

[triblondon]

I will ship a fix for polyfillpolyfill/polyfill-service#561

[gaearon]

What is the planned fix? Is it future proof?

[apaleslimghost]

polyfillpolyfill/polyfill-service#561 (comment)

[ForbesLindesay]

I wonder if a better fallback would be to hedge slightly and deliver at least the most commonly needed polyfills, rather than delivering no polyfills.

[gaearon]

I don’t understand the problem space that well, would the proposed fix also work for Twitter / Slack / LinkedIn / ...?