Cache npm packages in CI

.github/actions/install-ci-dependencies/action.yml

@@ -1,10 +1,10 @@
 name: Install Azure Linux CI dependencies
-description: Restore and populate the Azure Linux package cache
+description: Restore and populate the Azure Linux RPM and npm package caches
 
 runs:
   using: composite
   steps:
-    - name: Configure package cache
+    - name: Configure RPM package cache
       id: configure
       shell: bash
       run: |
@@ -73,7 +73,7 @@ runs:
         echo "package-manager=$package_manager" >> "$GITHUB_OUTPUT"
         echo "setup-script=$setup_script" >> "$GITHUB_OUTPUT"
 
-    - name: Restore package cache
+    - name: Restore RPM package cache
       continue-on-error: true
       uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
       with:
@@ -83,6 +83,17 @@ runs:
           azure-linux-${{ steps.configure.outputs.package-manager }}-rpms-${{ runner.arch }}-${{ hashFiles('scripts/setup-ci*.sh') }}-
           azure-linux-${{ steps.configure.outputs.package-manager }}-rpms-${{ runner.arch }}-
 
+    - name: Restore npm package cache
+      continue-on-error: true
+      uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
+      with:
+        path: /github/home/.npm
+        key: azure-linux-npm-packages-${{ runner.arch }}-${{ hashFiles('**/package.json', 'scripts/prettier-checks.sh') }}-${{ github.job }}-${{ steps.configure.outputs.cache-week }}
+        restore-keys: |
+          azure-linux-npm-packages-${{ runner.arch }}-${{ hashFiles('**/package.json', 'scripts/prettier-checks.sh') }}-${{ github.job }}-
+          azure-linux-npm-packages-${{ runner.arch }}-${{ hashFiles('**/package.json', 'scripts/prettier-checks.sh') }}-
+          azure-linux-npm-packages-${{ runner.arch }}-
+
     - name: Install dependencies
       shell: bash
       env:

.github/workflows/README.md

@@ -4,9 +4,9 @@ Documents the various GitHub Actions workflows, the role they fulfill and 3rd pa
 
 ## Azure Linux CI dependencies
 
-The local composite action in `.github/actions/install-ci-dependencies/action.yml` installs Azure Linux 3 and 4 CI dependencies and caches downloaded RPMs. Its cache key separates package managers and runner architectures, includes a hash of `scripts/setup-ci*.sh`, and includes the date of the most recent Sunday at midnight UTC. The weekly date makes GitHub Actions create a refreshed immutable cache each week.
+The local composite action in `.github/actions/install-ci-dependencies/action.yml` installs Azure Linux 3 and 4 CI dependencies and caches downloaded RPM and npm packages. Cache keys separate runner architectures, hash the relevant dependency inputs, and include the date of the most recent Sunday at midnight UTC. The RPM key also separates package managers, while the npm key separates jobs so each job can save the packages it downloads. The weekly date makes GitHub Actions create refreshed immutable caches each week.
 
-At a weekly rollover, restore keys first reuse the latest cache for the same dependency scripts and then fall back to any cache for the same package manager and architecture. The package manager refreshes repository metadata and downloads only missing or updated RPMs. `actions/cache` saves the populated directory automatically after a successful job when the exact weekly key was not restored.
+At a weekly rollover, restore keys first reuse the latest cache for the same dependency inputs and then fall back to a compatible cache for the same architecture. The package managers refresh registry metadata and download only missing or updated packages. `actions/cache` saves each populated directory automatically after a successful job when the exact weekly key was not restored.
 
 # Maintained