Merge pull request #571 from Automattic/add/eslint

Add eslint

Author: cojennin

.eslines.json

@@ -0,0 +1,11 @@
+{
+    "branches": {
+        "default": ["downgrade-unmodified-lines"]
+    },
+    "processors": {
+        "downgrade-unmodified-lines": {
+            "remote": "origin/master",
+            "rulesNotToDowngrade": ["no-unused-vars"]
+        }
+    }
+}

.travis.yml

@@ -44,6 +44,10 @@ before_script:
     - bash bin/install-wp-tests.sh wordpress_test root '' localhost $WP_VERSION
     - export COMPOSER_BIN_DIR="$HOME/.config/composer/vendor/bin"
     - export PATH="$COMPOSER_BIN_DIR:$PATH"
+    - |
+        if [[ ${RUN_PHPCS} == "1" ]]; then
+          npm install
+        fi
     - |
         if [[ ${TRAVIS_PHP_VERSION:0:2} == "7." ]]; then
           composer global require "phpunit/phpunit=5.7.*"
@@ -55,6 +59,7 @@ script:
   - |
       if [[ ${TRAVIS_PHP_VERSION:0:2} == "7." ]] && [[ ${RUN_PHPCS} == "1" ]]; then
         bash bin/phpcs-diff.sh
+        npm run lint
       fi
   - phpunit