Meeting Notes 2021-11-16

[afoxman]

Meeting Notes

Recording is posted to our Teams channel

Docs: Metro as a web bundler

Stripe is polishing the underlying code, and will then work on writing and upstreaming documentation.

Hash-based Metro module IDs

AirBNB wants to upstream, but no news yet.

Docs: Using the metro cache with S3

Microsoft to connect with AirBNB/Stripe to understand the system and document it.

Haste-map replacement experiments

Meta is incorporating plans into their roadmap.

Bundle-size reduction using tree-shaking and bundle-splitting

Callstack is using ESBuild with Webpack. Bundle-size redution compared to Webpack, but not vs. ESBuild standalone.

AirBNB experimented with Web tree-shaking and came close (70-80%) of the small bundle size produced by Webpack.

Expo for Web: ship as ES modules, then transpile for Expo. Expo uses Webpack which tree-shakes best with package.json fields like sideEffects. If Hermes had ES module support, it could improve tree-shaking.

Meta (Facebook) explored adding a module system to Hermes vs. currently using a polyfill to create a bundle. Investigating ideas around JS to JS transpilation and whole-program optimization.

require() cycle detection in Metro

PR is in progress (external author).

Bundle output formats: ES modules, Hermes byte-code, etc.

Meta: In the Web space, ES module production makes sense. In the react-native space, producing Hermes bytecode is the path forward. Still early days.

Metro: Roadmap

Most near-term work will be internal, and will lead to published work in the future. Working to align with React on a multi-platform framework.

Improve Metro docs and cleaning up code. Includes deep-dive articles on topics like module resolution and configuation options.

Interested in optimizing startup - decoupling Haste to eliminate crawl.

Node 17 "exports" and package.json visibility

Will have an impact on tools/projects which do module resolution. Developer community doesn't seem too happy with the whole thing.

Bug: nodejs/node#33460
Docs: https://nodejs.org/api/packages.html#conditional-exports