Support "syntheticNamedExports"?

[hyrious]

It is about importing named exports from commonjs modules, similar to this rollup feature.

// a.js, with { syntheticNamedExports: '__exports' } info
var foo = 1
var __exports = { bar: 2 }
export { foo, __exports }

// main.js
import { foo, bar, buzz } from "./a.js"
foo  // 1
bar  // 2, equal to __exports['bar']
buzz // undefined, equal to __exports['buzz']

It's good to know if you plan to support this feature, or as non-goal.

[evanw]

No, I'm not planning on supporting that feature at the moment. That's not how the JavaScript specification works and esbuild tries to follow the specification. Note that esbuild's bundler already supports importing named exports from CommonJS modules without needing a mechanism like this.

[hyrious]

Yes esbuild can bundle cjs module with named imports, with the downside of no tree-shaking on the cjs modules. This feature allows to mark a named export in es module as "module.exports", so that the input are all esm and tree-shaking still happens.

Rollup made this to support re-export in its commonjs plugin, so that it doesn't have to analyse too deep. I recently tried to repeat that plugin in esbuild and find that it requires such feature to be enabled in plugin side.

Anyway, it's ok if you're not planning to support it.

[evanw]

Closing as out of scope.