CI: Add build step.

.github/workflows/build.yml

@@ -0,0 +1,29 @@
+name: Build
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+jobs:
+  javascript:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [16.x]
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Build
+        run: npm run build