fixed build workflow

.github/workflows/build.yml

@@ -1,16 +0,0 @@
-name: Build JavaScript assets
-
-on:
-  push:
-    branches:
-      - master
-
-jobs:
-  build:
-    runs-on: ubuntu-latest
-
-    steps:
-      - uses: actions/checkout@master
-      - uses: flarum/action-build@master
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/js.yml

@@ -0,0 +1,66 @@
+name: JS
+
+on: [workflow_dispatch, push, pull_request]
+
+env:
+  NODE_VERSION: 16
+
+jobs:
+  build-prod:
+    name: Build and commit
+    runs-on: ubuntu-latest
+
+    # Only commit JS on push to master branch
+    # Remember to change in `build-test` job too
+    if: github.ref == 'refs/heads/master' && 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: 'yarn'
+          cache-dependency-path: js/yarn.lock
+
+      # Our action will install node, npm and yarn, cd into `./js`, run `yarn run build` (and
+      # `yarn run build-typings` if desired), 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: yarn
+          # typings_script: build-typings
+
+  build-test:
+    name: Test build
+    runs-on: ubuntu-latest
+
+    # Inverse check of `build-prod`
+    # Remember to change in `build-prod` job too
+    if: github.ref != 'refs/heads/master' || 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: 'yarn'
+          cache-dependency-path: js/yarn.lock
+
+      # Our action will install node, npm and yarn, cd into `./js`, run `yarn run build` (and
+      # `yarn run build-typings` if desired). It will NOT commit and upload.
+      - name: Build production JS
+        uses: flarum/action-build@2
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          build_script: build
+          package_manager: yarn
+          # typings_script: build-typings
+          do_not_commit: true