build: postprocess declaration imports to include .mjs extension for NodeNext/Node16 TS resolution (#110)

Author: cursoragent

build/bundle.ts

@@ -208,6 +208,26 @@ async function bundleDeclarations() {
   await execa("shx", ["rm", `${rootDir}/dist/index.js`])
 }
 
+async function fixDeclarationImports() {
+  info("Fixing declaration import extensions for NodeNext")
+  const files = [
+    `${rootDir}/dist/react/index.d.ts`,
+    `${rootDir}/dist/preact/index.d.ts`,
+    `${rootDir}/dist/solid/index.d.ts`,
+    `${rootDir}/dist/vue/index.d.ts`,
+    `${rootDir}/dist/angular/index.d.ts`,
+  ]
+  for (const file of files) {
+    try {
+      let raw = await readFile(file, "utf8")
+      raw = raw.replace(/from '\.\.\/index'"?/g, "from '../index.mjs'")
+      await writeFile(file, raw)
+    } catch (e) {
+      error(`Failed to postprocess ${file}: ${(e as Error).message}`)
+    }
+  }
+}
+
 async function addPackageJSON() {
   info("Writing package.json")
   const raw = await readFile(resolve(rootDir, "package.json"), "utf8")
@@ -302,6 +322,7 @@ async function main() {
   // await qwikBuild()
   await declarationsBuild()
   await bundleDeclarations()
+  await fixDeclarationImports()
   await nuxtBuild()
   await addPackageJSON()
   await addAssets()