Migrate from @babel/polyfill to core-js@3

[ChristophWurst]

Ref 🔖 https://babeljs.io/blog/2019/03/19/7.4.0

Supersedes #19842

[ChristophWurst]

FYI the main.js bundle shrinks from 1328kB to 1240kB = ~7% 🚀

[juliusknorr]

Does not work in IE11 anymore:

Mainly it seems that Object.assign is no longer properly polyfilled

[ChristophWurst]

Does not work in IE11 anymore

Huh. Is it because with corejs only the bundled files are polyfilled and anything external isn't? 😢

[juliusknorr]

Probably, I just checked the login page and it was an Object.assign in backbone.js that caused that.

[ChristophWurst]

Okay. Then we can either

• Close this PR and proceed with what we had before
• Change this PR to still ship the full-fledged polyfill but also just inline the corejs usage for bundled files

[juliusknorr]

Not sure if that fixes it but maybe we could also make sure that the affected node modules are transpiled as well? https://github.com/nextcloud/server/blob/master/webpack.common.js#L86

[ChristophWurst]

It will help with the packages where we know that transpilation is requried. But anything else might break. I think the safe path is to still ship a polyfill.

On that note. We might want to document that apps shouldn't rely on it, so we can phase that out?

[skjnldsv]

You also need other stuff to replace polyfill:
https://babeljs.io/docs/en/babel-polyfill

import "core-js/stable";
import "regenerator-runtime/runtime";

[ChristophWurst]

FYI the main.js bundle shrinks from 1328kB to 1240kB = ~7% rocket

Now we're at 1356kB :rocket_crashing:

[ChristophWurst]

Mainly it seems that Object.assign is no longer properly polyfilled

Tested again with IE11, Object.assign was there :)

[gary-kim]

LGTM. I am a bit worried about this but it looks like other people have write access so it should still be supported.

EDIT: TLDR, the author and primary maintainer of the project has been sentenced to 1.5 years in prison.

[ChristophWurst]

LGTM. I am a bit worried about this but it looks like other people have write access so it should still be supported.

Ouch. Didn't know about that. As the polyfill is deprecated this is our best choice right now. If alternatives evolve, we should be able to migrate to them.