build: extract bundle scripts into js modules

package.json

@@ -48,9 +48,11 @@
     "tinyglobby": "^0.2.10",
     "typescript": "^5.7.2"
   },
-  "dependencies": {
+  "optionalDependencies": {
     "@nodelib/fs.stat": "^4.0.0",
-    "@nodelib/fs.walk": "^3.0.0",
+    "@nodelib/fs.walk": "^3.0.1"
+  },
+  "dependencies": {
     "glob-parent": "^6.0.2",
     "merge2": "^1.4.1",
     "micromatch": "^4.0.8"
@@ -67,8 +69,8 @@
     "_build:compile": "npm run clean && npm run compile",
     "build": "npm run _build:compile && npm run lint && npm test",
     "watch": "npm run _build:compile -- -- --sourceMap --watch",
-    "_bundle:dts": "dts-bundle-generator ./src/index.ts --out-file=./build/index.d.ts --export-referenced-types=false --external-inlines=@nodelib/fs.walk @nodelib/fs.scandir @nodelib/fs.stat",
-    "_bundle:js": "esbuild --bundle ./out/index.js --outfile=./build/index.js --platform=node --target=node18.18 --format=cjs",
+    "_bundle:dts": "node ./scripts/bundle-dts.mjs",
+    "_bundle:js": "node ./scripts/bundle-js.mjs",
     "_bundle:build": "npm run _bundle:dts && npm run _bundle:js",
     "_bundle:test:replace": "cp ./build/index.js ./out",
     "_bundle:test": "npm run _bundle:test:replace",

scripts/bundle-dts.mjs

@@ -0,0 +1,30 @@
+import * as fs from 'node:fs';
+
+import dbg from 'dts-bundle-generator';
+
+const [declarations] = dbg.generateDtsBundle([
+	{
+		filePath: './src/index.ts',
+		libraries: {
+			inlinedLibraries: [
+				'@nodelib/fs.stat',
+				'@nodelib/fs.scandir',
+				'@nodelib/fs.walk',
+			],
+		},
+		output: {
+			exportReferencedTypes: false,
+		},
+	},
+]);
+
+const imports = declarations.match(/from\s'(?<filepath>[^']+)'/g);
+
+const hasOnlyNodeDependencies = imports.every((it) => it.startsWith("from 'node:"));
+
+if (!hasOnlyNodeDependencies) {
+	throw new Error('Not only node: dependencies are found in the dts bundle.');
+}
+
+fs.mkdirSync('./build', { recursive: true });
+fs.writeFileSync('./build/index.d.ts', declarations, 'utf8');

scripts/bundle-js.mjs

@@ -0,0 +1,13 @@
+import esbuild from 'esbuild';
+
+import package_ from '../package.json' with { type: 'json' };
+
+await esbuild.build({
+	bundle: true,
+	platform: 'node',
+	target: 'node18.18',
+	format: 'cjs',
+	external: Object.keys(package_.dependencies),
+	entryPoints: ['./out/index.js'],
+	outfile: './build/index.js',
+});