ci: update workflow to run on `main`

.github/workflows/build.yml

@@ -1,17 +1,91 @@
-name: Build JavaScript assets
+name: JS
 
-on:
-  push:
-    branches:
-      - master
+on: [workflow_dispatch, push, pull_request]
+
+env:
+  NODE_VERSION: 16
 
 jobs:
-  build:
+  prettier:
+    name: Prettier
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@master
-      - uses: flarum/action-build@master
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Check out code
+        uses: actions/checkout@v2
 
+      - name: Set up Node
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+          cache: "npm"
+          cache-dependency-path: js/package-lock.json
+
+      - name: Install JS dependencies
+        run: npm ci
+        working-directory: ./js
+
+      - name: Check JS formatting
+        run: npm run format-check
+        working-directory: ./js
+
+  build-prod:
+    name: Build and commit
+    runs-on: ubuntu-latest
+    needs: [prettier]
+
+    # Only commit JS on push to master branch
+    # Remember to change in `build-test` job too
+    if: github.ref == 'refs/heads/main' && github.event_name == 'push'
+
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v2
+
+      - name: Set up Node
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+          cache: "npm"
+          cache-dependency-path: js/package-lock.json
+
+      # Our action will install npm, cd into `./js`, run `npm run build` and
+      # `npm run build-typings`, then commit and upload any changes
+      - name: Build production JS
+        uses: flarum/action-build@2
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          build_script: build
+          package_manager: npm
+          # typings_script: build-typings
+
+  build-test:
+    name: Test build
+    runs-on: ubuntu-latest
+    needs: [prettier]
+
+    # Inverse check of `build-prod`
+    # Remember to change in `build-prod` job too
+    if: github.ref != 'refs/heads/main' || github.event_name != 'push'
+
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v2
+
+      - name: Set up Node
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+          cache: "npm"
+          cache-dependency-path: js/package-lock.json
+
+      # Our action will install npm, cd into `./js`, run `npm run build` and
+      # `npm run build-typings`, then commit and upload any changes
+      - name: Build production JS
+        uses: flarum/action-build@2
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          build_script: build
+          package_manager: npm
+          # typings_script: build-typings
+          do_not_commit: true