Shared prettier config (ghostery#827)

.github/workflows/test-libs.yml

@@ -0,0 +1,23 @@
+name: Test libs
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test-libs:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: libs
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v2
+        with:
+          node-version: '18'
+          cache: 'npm'
+          cache-dependency-path: ./libs/package-lock.json
+      - run: npm ci
+      - run: npm run lint

libs/.eslintrc

@@ -0,0 +1,16 @@
+{
+  "env": {
+    "es2020": true,
+    "browser": true,
+    "serviceworker": true,
+    "webextensions": true,
+    "mocha": true
+  },
+  "extends": [
+    "eslint:recommended",
+    "plugin:prettier/recommended"
+  ],
+  "parserOptions": {
+    "sourceType": "module"
+  }
+}