Bundler support track

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Bundler supports

Tracking the bundler supports for the optimal artifact (webpack¹ and Rspack).

CJS support

ESM artifacts won't break by scope isolation when bundling module bailout from concatenation (usually CJS module).

• webpack: feat: root module is less prone to be wrapped in IIFE webpack/webpack#18348
• Rspack: feat: root module is less prone to be wrapped in IIFE rspack#6697

Tree shakable export

ESM artifacts should be tree-shakable.

• webpack: feat: tree shakable output for module library webpack/webpack#18272
• Rspack: feat: tree shakable output for module library rspack#6877

Remove unnecessary webpack exports runtime

• webpack: fix: only render init code when need moduleRemapping webpack/webpack#18338
• webpack: feat: reduce unnecessary exports runtime webpack/webpack#18565
• Rspack: feat: reduce unnecessary exports runtime rspack#7102

Externals ^P0

Externalized module import / dynamic import will introduce redundant runtime in webpack / Rspack. Dynamic import will be hoisted to the top level (webpack/webpack#17986). Furthermore, the import and import() should be leave unchanged.

• support "module-import" external type
  • webpack: feat: add new external type "module-import" webpack/webpack#18620
  • Rspack: feat: port "module-import" external type rspack#7479
• Rspack misaligned: Port fix: only render init code when need moduleRemapping webpack/webpack#18338. However, the simple module remapping runtime in Rspack (https://github.com/web-infra-dev/rspack/blob/main/crates/rspack_core/src/external_module.rs#L266-L269) is totally unused now.
  • Rspack: fix: remove useless "module" external runtime rspack#7533
• dynamic external introduce webpack runtime
  • Rspack: feat(modern-module): make dynamic import runtime-less rspack#7759
• In concatenated module, static external module namespace import re-assign breaks tree shaking (demo)
  • Rspack: fix: avoid import external module re-assigin in concatenation rspack#7839
• Not work with star export from external module (bundleless) Preserve star exports for externalized dependencies in module output webpack/webpack#15270
• preserve import() when import() is supported in that Node.js version in CJS. (BLOCK: can't distinguish static / dynamic from external callback except adding new information) Allow Dynamic Import in `commonjs2` webpack/webpack#16272
  • webpack: https://redirect.github.com/webpack/webpack/pull/18784

Dynamic import (Chunk splitting) ^P1

Can't be static analysis because of the public path runtime.

• Output statically resolvable dynamic import expressions webpack/webpack#15697
• Single runtime chunk incompatible with library output in Webpack 5 webpack/webpack#12801

Preserve CSS Import

CSS import statement will be extracted out.

Node.js Shims

• feat(node-stuff): implement node-module shim rspack#7465

Miscellaneous

require

• Rspack: feat(parser): add new javascript parser options rspack#7939

require and require.resolve

• ESM:
  • require(...) should be either behave like esbuild (sniff and throw as a fallback) or be shimmed with createRequire.
  • require.resolve(...) should be either behave like esbuild (sniff and throw as a fallback) or be shimmed with createRequire.
• CJS:
  • require(...) with externals should work like __non_webpack_require__
  • require.resolve(...) should preserve as-is.
  • preserve require('./' + expression + '.js') like dynamic require with expression. (BLOCK: https://github.com/microsoft/rushstack/blob/main/webpack/preserve-dynamic-require-plugin/README.md not available in Rspack as succeedModule is readonly in JS side)

Extra runtime when bundling single module

• Rspack: feat(modern-module): force concaten single module rspack#7317
• Rspack: fix(modern-module): compat with more export cases rspack#7394

Re-export with property access or eval

• Rspack: fix(modern-module): compat with more export cases rspack#7394

Multiple entries ^P2

Export in library works only for last entry module

• export in library works only for last entry module webpack/webpack#15936

Footnotes

1. Reference: https://github.com/webpack/webpack/issues/17121 ↩

[fi3ework]

🚧 ESM output quality track

Not aim to strict alignment with esbuild, compare the differences between esbuild artifacts and create a more compact output.