サンプル

Configure @babel/preset-env options, handling removed legacy settings useBuiltIns and bugfixes in Babel 8 while controlling module formats, forced transforms, and plugin selection

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PUBLISHED L3_CONTRACT_PASS MIT-0

ケース

ゴール: Configure @babel/preset-env options, handling removed legacy settings useBuiltIns and bugfixes in Babel 8 while controlling module formats, forced transforms, and plugin selection HOW
パッケージ: @babel/preset-env 8.0.2 @babel/core 8.0.1
環境: node
作成日: 2026-08-17T01:45:38Z

Passing useBuiltIns: 'usage' or bugfixes: true to @babel/preset-env automatically injects core-js polyfills and activates targeted syntax bugfixes.

このサンプルの作者が、ここで開発者やモデルが期待するであろうこととして記録したもの。下の契約が実際に実行されたものだ。

Passing useBuiltIns: 'usage' or 'entry' throws an error because polyfill injection has been removed from @babel/preset-env, and passing bugfixes throws because bugfix transforms are now unconditionally active.
Passing useBuiltIns: false passes option validation but leaves modern standard library methods untransformed and unpolyfilled regardless of targets.
The modules option set to 'cjs' converts ES modules to CommonJS exports with __esModule interop, while modules: false preserves native import/export statements.
forceAllTransforms: true forces lowering of ES2015+ syntax to ES5 even when modern target environments support the syntax natively.
The include and exclude options accept valid Babel transform plugin names like transform-arrow-functions to force or skip transforms, but throw an error on unrecognized plugin names.

node 22 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17 · ed25519:d91480838ac982c9