Add caching of dependencies to GitHub actions

Author: hkdobrev

.github/workflows/js_test.yml

@@ -4,18 +4,29 @@ on: [push]
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v1
+    - name: Cache
+      id: cache
+      uses: actions/[email protected]
+      with:
+        path: node_modules
+        key: ${{ runner.OS }}-build-${{ hashFiles('**/package-lock.json') }}
+        restore-keys: |
+          ${{ runner.OS }}-build-${{ env.cache-name }}-
+          ${{ runner.OS }}-build-
+          ${{ runner.OS }}-
     - name: Use Node.js ${{ matrix.node-version }}
       uses: actions/setup-node@v1
       with:
         node-version: 12
-    - name: npm install, build, and test
-      run: |
-        npm ci
-        npm run build --if-present
-        npm test
+    - name: Install Dependencies
+      if: steps.cache.outputs.cache-hit != 'true'
+      run: npm ci
+      env:
+        CI: true
+    - name: npm test
+      run: npm test
       env:
         CI: true