add .github/workflows/

.github/workflows/node.js.yml

@@ -0,0 +1,33 @@
+# cf.
+# https://docs.github.com/en/actions/automating-builds-and-tests/building-and-testing-nodejs#starting-with-the-nodejs-workflow-template
+# https://dev.classmethod.jp/articles/caching-dependencies-in-workflow-execution-on-github-actions/
+name: CI via GitHub Actions
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [16]
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-node@v3
+        with:
+          node-version: ${{ matrix.node-version }}
+      - uses: actions/cache@v3
+        id: node_modules_cache_id
+        env:
+          cache-name: cache-node-modules
+        with:
+          path: '**/node_modules'
+          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/package-lock.json') }}
+      - run: echo '${{ toJSON(steps.node_modules_cache_id.outputs) }}'
+      - if: ${{ steps.node_modules_cache_id.outputs.cache-hit != 'true' }}
+        run: npm install
+      - run: npm test