Added js linter config.

docker-compose.yml

@@ -0,0 +1,12 @@
+version: '2'
+
+services:
+    xo-js-lint:
+        build: linting/js
+        image: patek-devs/eslint-xo
+        command: . --env=browser --extend=/eslintrc.yml
+        volumes:
+            - ./themes/patek/assets/js:/src:ro
+            - ./linting/js/eslintrc.yml:/eslintrc.yml
+
+

linting/js/Dockerfile

@@ -0,0 +1,20 @@
+FROM node:12-alpine
+
+RUN mkdir /src
+
+# Hack to upgrade NPM:
+#  - install local version
+#  - replace old global verson with new one
+
+RUN npm install npm@5.3 && \
+    rm -rf /usr/local/lib/node_modules/npm && \
+    mv /node_modules/npm  /usr/local/lib/node_modules
+
+RUN npm install -g xo@0.24.0
+
+# Cleanup
+RUN rm -fr /root/.npm /node_modules
+
+WORKDIR /src
+
+ENTRYPOINT ["/usr/local/bin/xo"]

linting/js/eslintrc.yml

@@ -0,0 +1,6 @@
+rules:
+    quotes:
+        - error
+        - double
+    unicorn/prefer-query-selector: off
+    no-negated-condition: off