Add action

.github/workflows/build.yml

@@ -0,0 +1,24 @@
+name: NodeJS with Grunt
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Use Node.js
+      uses: actions/setup-node@v1
+      with:
+        node-version-file: '.nvmrc'
+
+    - name: Build
+      run: |
+        npm install
+        npm run build

package.json

@@ -7,6 +7,7 @@
     "url": "https://github.com/mathigon/parallel.git"
   },
   "scripts": {
+    "build": "grunt build",
     "start": "grunt build && npm run serve",
     "serve": "grunt concurrent & firebase serve",
     "export-users": "firebase auth:export ./private/tmp-users.json --format=json",