specify module type in compiled output (#88)

Author: copperlight

Diff for: README.md

@@ -22,5 +22,8 @@ Install a version of [Node.js] >= 18, possibly with [Homebrew] or [nvm].
 npm run build-and-test
 ```
 
+Followed the advice in [Supporting CommonJS and ESM with Typescript and Node] to produce both CJS and ESM output.
+
 [Homebrew]: https://brew.sh/
 [nvm]: https://github.com/nvm-sh/nvm
+[Supporting CommonJS and ESM with Typescript and Node]: https://evertpot.com/universal-commonjs-esm-typescript-packages/

Diff for: package.json

@@ -1,19 +1,27 @@
 {
   "name": "nflx-spectator",
-  "version": "3.0.0-rc.5",
+  "version": "3.0.0-rc.6",
   "license": "Apache-2.0",
   "homepage": "https://github.com/Netflix/spectator-js",
   "author": "Netflix Telemetry Engineering <[email protected]>",
   "type": "module",
   "main": "cjs/src/index.js",
   "types": "esm/src/index.d.ts",
   "exports": {
-    "import": "./esm/src/index.js",
-    "require": "./cjs/src/index.js"
+    ".": {
+      "import": {
+        "default": "./cjs/src/index.js",
+        "types": "./cjs/src/index.d.ts"
+      },
+      "require": {
+        "default": "./esm/src/index.js",
+        "types": "./esm/src/index.d.ts"
+      }
+    }
   },
   "files": [
     "esm/src/**/*",
-    "cjs/src/**/*.js"
+    "cjs/src/**/*"
   ],
   "engines": {
     "node": ">=18.0.0"
@@ -36,7 +44,9 @@
   },
   "scripts": {
     "clean": "rm -rf cjs coverage esm",
-    "build": "tsc --module commonjs --outDir cjs; tsc --module es2022 --outDir esm",
+    "build-cjs": "tsc --module commonjs --outDir cjs; echo '{\"type\": \"commonjs\"}' > cjs/package.json",
+    "build-esm": "tsc --module es2022 --outDir esm; echo '{\"type\": \"module\"}' > esm/package.json",
+    "build": "npm run build-cjs; npm run build-esm",
     "build-and-test": "npm run build; npm run test",
     "lint": "eslint 'src/**/*.ts' 'test/**/*.ts'",
     "test": "mocha 'esm/test/**/*.test.js'",