[pkg] Package as esm

Author: Patrick-Clausen

.gitignore

@@ -1,2 +1,3 @@
 node_modules
 coverage
+dist

package.json

@@ -3,9 +3,12 @@
   "version": "1.0.0",
   "description": "Check if a protocol requires a certain port number to be added to an URL.",
   "main": "index.js",
+  "module": "./dist/index.mjs",
   "scripts": {
     "test": "c8 --reporter=lcov --reporter=text mocha test.js",
-    "watch": "mocha --watch test.js"
+    "build-esm": "esbuild index.js --outfile=dist/index.mjs --format=esm",
+    "watch": "mocha --watch test.js",
+    "prepublishOnly": "npm run build-esm"
   },
   "repository": {
     "type": "git",
@@ -38,6 +41,7 @@
   "devDependencies": {
     "assume": "~2.3.0",
     "c8": "~7.12.0",
+    "esbuild": "^0.17.18",
     "mocha": "~10.2.0",
     "pre-commit": "~1.2.0"
   }