Specify commonjs in tsconfig.json

tsconfig.json

@@ -6,7 +6,7 @@
     "experimentalDecorators": true,
     "jsx": "react",
     "lib": ["es6", "dom"],
-    "module": "es6",
+    "module": "commonjs",
     "moduleResolution": "node",
     "sourceMap": true,
     "target": "es6"