add packages

frontend/packages/app/package.json

@@ -0,0 +1,9 @@
+{
+    "name": "@backstage/app",
+    "version": "0.0.0",
+    "main": "./src/index.js",
+    "dependencies": {
+        "@backstage/core": "0.0.0",
+        "react": "^16.12.0"
+    }
+}

frontend/packages/app/src/index.js

@@ -0,0 +1,3 @@
+const core = require('@backstage/core');
+
+console.log(core());

frontend/packages/core/package.json

@@ -0,0 +1,5 @@
+{
+    "name": "@backstage/core",
+    "version": "0.0.0",
+    "main": "./src/index.js"
+}

frontend/packages/core/src/index.js

@@ -0,0 +1,3 @@
+module.exports = function () {
+    return "hello world!";
+}