Add CI for builds and tests

.github/workflows/node.js.yml

@@ -0,0 +1,27 @@
+# Credits to https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-nodejs
+# for the code.
+
+name: Node.js CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Use Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20.x'
+      - run: npm ci
+      - run: npm run build --if-present
+      - run: npm test