Relay: Two core-js dependencies

[dmnd]

Relay depends on core-js twice:

1. relay -> babel-runtime ^6.6.1 -> core-js ^2.1.0
2. relay -> fbjs ^0.8.1 -> core-js ^1.0.0

These two versions aren't semver compatible, so it means a project that includes relay will have two copies of core-js in use. It'd be nice to collapse this dependency into a single version of core-js.

You can probably fix this by depending on fbjs 0.9.0-alpha.1 but maybe that's labelled alpha for a reason?

[wincent]

Well spotted! Thanks for bringing this up @dmnd.

Some dev dependencies (like react, react-dom) end up depending on a non-alpha version of fbjs. I know they're just dev dependencies, but I'm inclined to wait until the next major updates there as well and do it all in one fell swoop. What do you think?

[dmnd]

I'm using Relay in production, so in the interest of asset sizes, I'd prefer to collapse the duplicate dependencies sooner where possible 😉

Who do we need to convince to release a proper version of fbjs?

[wincent]

First thing's first is probably opening an issue on the repo, but I see you just did that... I can also ping internally to ask why we have the alpha release at all anyway (it's not tagged in GitHub).

[yasserkaddour]

I don't think the double dependency is much of an issue since fbjs only uses es6/set and es6/map for a total of ~9kb, whereas the latest version of babel-polyfill import all the core-js library for a total of ~89kb.
I think sticking to an earlier version of babel-polyfill would be better, I just tried successfully babel-es6-polyfill now core-js is ~25kb, I think knowing what is exactly needed in core-js would reduce the bundle size further.

Speaking of bundle size; I hope relay 2 will be sensible to it, and would allow modular import; ~214kb / ~75kb gziped is a bit too much. And Preact compatibility would be super https://github.com/developit/preact/issues/411.

I am really exited about relay 2! Keep up the good work :+1: Thanks

[wincent]

Yep @YasserKaddour. I'd like to see more granular modular imports moving forward too. Let's make it happen.

[yasserkaddour]

:tada: @wincent good to hear. Can I know what babel-polyfill is used for exactly ? Thanks

[wincent]

@YasserKaddour, I believe it provides the regenerator runtime (which we're not currently using, but could use in the future for async support) and the so-called core-js package, which has a broad set of ES5/ES6 polyfills. At some point it would be desirable to make it possible to bring-your-own-polyfill, so that if users knew they only had to support modern environments they could just drop the polyfill altogether.

[mattecapu]

+1 for the size reduction
Relay takes currently about a quarter of my app bundle

[yasserkaddour]

Sorry, I wasn't clear; I wanted to know what subset of es5/es6 function is used by relay? and why use a polyfill instead of a transpiler?
Aren't we already bringing our own polyfill since it up to the user to add import 'babel-polyfill' in his app, and chose what version to install?

[wincent]

I wanted to know what subset of es5/es6 function is used by relay?

I could give you a semi-accurate answer off the top of my head, but your best bet is probably to have a skim through the source code and have a look.

[Ephys]

How soon do you think until we can provide our own polyfills? We have 3 differents versions of core-js in our bundle and it's wasting a lot of space.

Also one of those versions is causing relay to crash because Set.size is null:

console.log('+++++++ LOADING APP ++++++++');
console.log('native set', (new Set()).size);

const CoreJsSet = require('babel-runtime/core-js/set').default;
console.log('babel-runtime/core-js set', (new CoreJsSet()).size);

[sibelius]

@Ephys polyfills have been removed from relay

https://github.com/facebook/relay/pull/1870

[Ephys]

@sibelius Great to hear! Thank you