fix: runtime fallback (#590)

Co-authored-by: Jiachi Liu <[email protected]>

Author: himself65

src/constants.ts

@@ -31,6 +31,20 @@ export const runtimeExportConventions = new Set([
   // Browser only
   'browser',
 ])
+export const runtimeExportConventionsFallback = new Map<string, string[]>([
+  // ESM only runtime
+  ['workerd', ['import', 'default']],
+  ['edge-light', ['import', 'default']],
+  ['browser', ['import', 'default']],
+
+  // it could be CJS or ESM
+  ['electron', ['default']],
+  ['react-server', ['default']],
+  ['react-native', ['default']],
+  ['node', ['default']],
+  ['deno', ['default']],
+  ['bun', ['default']],
+])
 export const optimizeConventions = new Set(['development', 'production'])
 export const specialExportConventions = new Set([
   ...runtimeExportConventions,

src/plugins/alias-plugin.ts

@@ -3,7 +3,10 @@ import { Entries } from '../types'
 import { posix } from 'path'
 import { relativify } from '../lib/format'
 import { getSpecialExportTypeFromConditionNames } from '../entries'
-import { specialExportConventions } from '../constants'
+import {
+  specialExportConventions,
+  runtimeExportConventionsFallback,
+} from '../constants'
 
 function hasNoSpecialCondition(conditionNames: Set<string>) {
   return [...conditionNames].every(
@@ -36,12 +39,21 @@ function findJsBundlePathCallback(
     conditionNames.has(specialCondition) ||
     (!conditionNames.has('default') && hasNoSpecialCondition(conditionNames))
 
-  return (
+  const match =
     isMatchedConditionWithFormat &&
     !isTypesCondName &&
     hasBundle &&
     isMatchedFormat
-  )
+  if (!match) {
+    const fallback = runtimeExportConventionsFallback.get(specialCondition)
+    if (!fallback) {
+      return false
+    } else {
+      return fallback.some((name) => conditionNames.has(name))
+    }
+  } else {
+    return match
+  }
 }
 
 function findTypesFileCallback({

test/integration/import-fallback/index.test.ts

@@ -0,0 +1,17 @@
+import { readFile } from 'fs/promises'
+import { createIntegrationTest } from '../utils'
+
+describe('integration import fallback', () => {
+  it('should handle import fallback', async () => {
+    await createIntegrationTest(
+      {
+        directory: __dirname,
+      },
+      async ({ distDir }) => {
+        const aEdgeLightFile = `${distDir}/a.edge-light.js`
+        const content = await readFile(aEdgeLightFile, { encoding: 'utf-8' })
+        expect(content).toMatch(/import '.\/b.js'/)
+      },
+    )
+  })
+})

test/integration/import-fallback/package.json

@@ -0,0 +1,11 @@
+{
+  "type": "module",
+  "exports": {
+    "./a": {
+      "edge-light": "./dist/a.edge-light.js"
+    },
+    "./b": {
+      "default": "./dist/b.js"
+    }
+  }
+}

test/integration/import-fallback/src/a/index.edge-light.js

@@ -0,0 +1 @@
+import '../b'

test/integration/import-fallback/src/b.js

@@ -0,0 +1 @@
+console.log('this is b')