feat: enable inline for CommonJS bundle (#2442)

* feat: enable inline for CommonJS bundle

* chore: add changeset

* chore: address eslint violations

Author: joshblack

.changeset/spicy-suits-help.md

@@ -0,0 +1,5 @@
+---
+'@primer/react': patch
+---
+
+Inline ESM-only dependencies in CommonJS bundle

package.json

@@ -63,6 +63,7 @@
     "codemods",
     "dist",
     "lib",
+    "lib/node_modules",
     "lib-esm",
     "index.d.ts",
     "drafts/package.json",

rollup.config.js

@@ -50,40 +50,22 @@ const input = new Set([
 ])
 
 const extensions = ['.js', '.jsx', '.ts', '.tsx']
-const external = [
+const ESM_ONLY = new Set(['@github/combobox-nav', '@github/markdown-toolbar-element', '@github/paste-markdown'])
+const dependencies = [
   ...Object.keys(packageJson.peerDependencies ?? {}),
   ...Object.keys(packageJson.dependencies ?? {}),
   ...Object.keys(packageJson.devDependencies ?? {})
 ]
-function isExternal(external) {
-  return id => {
-    // Match on import paths that are the same as dependencies listed in
-    // `package.json`
-    const match = external.find(pkg => {
-      return id === pkg
-    })
-
-    if (match) {
-      return true
-    }
 
-    // In some cases, there may be a subpath import from a module which should
-    // also be treated as external. For example:
-    //
-    // External: @primer/behaviors
-    // Import: @primer/behaviors/utils
-    return external.some(pkg => {
-      // Include the / to not match imports like: @primer/behaviors-for-acme/utils
-      return id.startsWith(`${pkg}/`)
-    })
-  }
+function createPackageRegex(name) {
+  return new RegExp(`^${name}(/.*)?`)
 }
 
 const baseConfig = {
   input: Array.from(input),
   plugins: [
-    // Note: it's important that the babel plugin is ordered first for plugins
-    // like babel-plugin-preval to work as-intended
+    // Note: it's important that the babel-plugin-preval is loaded first
+    // to work as-intended
     babel({
       extensions,
       exclude: /node_modules/,
@@ -116,7 +98,9 @@ const baseConfig = {
         ]
       ]
     }),
-    commonjs(),
+    commonjs({
+      extensions
+    }),
     resolve({
       extensions
     })
@@ -127,7 +111,7 @@ export default [
   // ESM
   {
     ...baseConfig,
-    external: isExternal(external),
+    external: dependencies.map(createPackageRegex),
     output: {
       dir: 'lib-esm',
       format: 'esm',
@@ -139,7 +123,7 @@ export default [
   // CommonJS
   {
     ...baseConfig,
-    external: isExternal(external),
+    external: dependencies.filter(name => !ESM_ONLY.has(name)).map(createPackageRegex),
     output: {
       dir: 'lib',
       format: 'commonjs',