[internal] Use the Node.js behavior for default imports #12795
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babel.config.js
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| @@ -382,3 +383,41 @@ function pluginPackageJsonMacro({ types: t }) { | |||
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| // Match the Node.js behavior (the default import is module.exports) | |||
| function pluginDefaultImportNode({ types: t }) { | |||
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This plugin transforms import foo from "mod" into const foo = require("mod"), which is what Node.js does.
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| @@ -158,6 +158,7 @@ module.exports = function (api) { | |||
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| convertESM ? "@babel/proposal-export-namespace-from" : null, | |||
| convertESM ? "@babel/transform-modules-commonjs" : null, | |||
| convertESM ? pluginNodeImportInterop : null, | |||
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Q: This plugin will be no-op for babel parser and some plugins bundled by Rollup, is that intended?
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It is not a problem because all the bundled packages don't have any third-party dependency. And even if they did, it would only be a problem if these third-party dependencies used __esModule.
However, I asked to reopen rollup/plugins#635 to add an option to @rollup/plugin-commonjs to mirror the Node.js behavior.
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I'm merging this PR with a single review since it's just internal bookkeeping and doesn't affect in any way our users. I will soon open a follow-up for |
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This is another step for #11701.
Node.s doesn't check if
__esModuleis defined when importing a CJS module from ESM, and thedefaultimport is always mapped tomodule.exports. This is different from how Babel handles the interop, and this PR aligns the compilation behavior to Node.js to make it easier to migrate to native ESM.We might also consider adding this as an option to
transform-modules-commonjs, but for now I just added a small internal plugin (not 100% compliant, because it doesn't hoist compiled imports) to our config.When this is merged, I will open a new PR to avoid using
__dirname/__filename/requirein our sources so that we'll only be using Node.js-compliant modules.