Bundler supports

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

(ESM) Tree shakable export

(ESM) ESM export 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

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

• 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

(ESM) 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

(ESM) Force concatenation single module

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

(ESM) Externals

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

  • Rspack: fix: preserve star export from external module rspack#8217

• 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
  • Rspack: feat(externals): support 'commonjs-import' type rspack#8414

(ESM) Avoid using namespace import for external module for better readability ^P0

• [Feature]: provide option to stop injecting __webpack_exports__ and __WEBPACK_EXTERNAL_MODULE_ variable prefix #869
• Unbundled esm output #806

(ESM) Dynamic import (Chunk splitting) ^P1

Static analysis is not possible due to the public path at runtime.

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

(ESM) Preserve CSS Import

• CSS import statement will be extracted out.

(ESM) Node.js Shims

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

(CJS) Support static analyzable export.

• webpack: fix(commonjs-static): export unprovided variables webpack/webpack#19303
• Rspack: fix(commonjs-static): export unprovided variables rspack#9630

(CJS / ESM) preserve 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)

(ESM) Re-export with property access or eval

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

(ESM) Multiple entries shares module graph

Multiple entries share the same module graph which will make bail out reason turn out to be a merge of all the entries and breaks the concatenation.

• [Bug]: Multiple entry files packaged esm file import error undefind #316

(ESM) Multiple entries ^P2

Export in library works only for last entry module

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

(ESM) Entry module demanding not to be bailed out.

• Entry module must not trigger concatenation bail out (such as contains eval expression), otherwise it will break the current "modern-module"'s ESM export premise.

non-Rslib related ESM feature support in Rspack

• HMR