drop cjs support, fix dynamic import in esm (#32)

* add webpackIgnore: true comment to dynamic import

* drop cjs support

.changeset/nine-tomatoes-smash.md

@@ -0,0 +1,5 @@
+---
+'@vercel/edge-config': major
+---
+
+drop cjs support

.changeset/olive-spiders-boil.md

@@ -0,0 +1,5 @@
+---
+'@vercel/edge-config': patch
+---
+
+fix dynamic import by adding webpackIgnore comment

package.json

@@ -6,11 +6,7 @@
   "license": "MIT",
   "sideEffects": false,
   "type": "module",
-  "exports": {
-    "import": "./dist/index.js",
-    "require": "./dist/index.cjs"
-  },
-  "main": "./dist/index.cjs",
+  "exports": "./dist/index.js",
   "module": "./dist/index.js",
   "types": "./dist/index.d.ts",
   "files": [

src/index.ts

@@ -85,7 +85,9 @@ async function getLocalEdgeConfig(
   edgeConfigId: string,
 ): Promise<EmbeddedEdgeConfig | null> {
   const embeddedEdgeConfigPath = `/opt/edge-configs/${edgeConfigId}.json`;
-  return import(embeddedEdgeConfigPath).catch(
+  // the webpackIgnore: true comment below gets dropped by esbuild,
+  // but we add it back in manually using the onSuccess callback
+  return import(/* webpackIgnore: true */ embeddedEdgeConfigPath).catch(
     () => null,
   ) as Promise<EmbeddedEdgeConfig | null>;
 }

tsup.config.js

@@ -1,14 +1,23 @@
+import fs from 'node:fs';
 import { defineConfig } from 'tsup';
 
 // eslint-disable-next-line import/no-default-export
 export default defineConfig({
   entry: ['src/index.ts'],
-  format: ['esm', 'cjs'],
+  format: ['esm'],
   splitting: true,
   sourcemap: false,
   minify: true,
   clean: true,
   skipNodeModulesBundle: true,
   dts: true,
   external: ['node_modules'],
+  onSuccess: () => {
+    const path = './dist/index.js';
+    const content = fs.readFileSync(path, 'utf-8');
+    fs.writeFileSync(
+      path,
+      content.replace('import(', 'import(/* webpackIgnore: true */'),
+    );
+  },
 });