Add node worklow

.github/workflows/nodejs.yml

@@ -1,20 +1,22 @@
-name: Node.js CI
-
-on: [push]
-
-jobs:
-  build:
-
-    runs-on: ubuntu-latest
-
-    steps:
-    - uses: actions/checkout@v1
-    - uses: actions/setup-node@v1
-      with:
-        node-version: 12.x
-    - run: npm install
-    - run: npm run build
-    - run: npm run lint
-    - run: npm test
-      env:
-        CI: true
+name: Node CI
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+    - uses: actions/setup-node@v1
+      with:
+        node-version: 12.x
+    - name: npm install, build, and test
+      run: |
+        npm ci
+        npm run build --if-present
+        npm run lint
+        npm test
+      env:
+        CI: true