Require TypeScript

Author: bobkorinek

package-lock.json

@@ -19,7 +19,8 @@
     "@types/node": "^14.14.36",
     "jsdom": "^16.5.1",
     "mocha": "^8.3.2",
-    "ts-node": "*"
+    "ts-node": "*",
+    "typescript": "^4.2.4"
   },
   "types": "index.d.ts",
   "main": ""