Add eslint with configuration

Also add overcommit rule for ESlint.

.jshintrc

@@ -1,4 +1,4 @@
 {
-  "esversion": 8,
+  "esversion": 9,
   "asi": true
 }

.overcommit.yml

@@ -37,6 +37,16 @@ PreCommit:
       - '**/*.jar'
       - '**/*.svg'
 
+  EsLint:
+    required_executable: 'WcaOnRails/bin/yarn'
+    enabled: true
+    include:
+      - 'WcaOnRails/app/javascript/**/*.js[x]'
+    exclude:
+      # FIXME: we could fix it, but it's long and it's legacy code anyway...
+      - 'WcaOnRails/app/javascript/edit-events/**/*.js[x]'
+    command: ['WcaOnRails/bin/yarn', 'run', 'eslint', '-c', '.eslintrc.json', '-f', 'compact']
+
   RuboCop:
     enabled: true
     on_warn: fail # Treat all warnings as failures
@@ -46,6 +56,9 @@ PreCommit:
 
   JsHint:
     enabled: true
+    include:
+      # Others are handled by EsLint
+      'WcaOnRails/app/assets'
     required_executable: 'WcaOnRails/bin/yarn'
     flags: ['run', '-s', 'jshint', '--verbose']
 

WcaOnRails/.eslintrc.json

@@ -0,0 +1,28 @@
+{
+    "env": {
+        "browser": true,
+        "es6": true,
+        "jquery": true
+    },
+    "extends": [
+        "plugin:react/recommended",
+        "airbnb"
+    ],
+    "globals": {
+        "Atomics": "readonly",
+        "SharedArrayBuffer": "readonly",
+        "_": true
+    },
+    "parserOptions": {
+        "ecmaFeatures": {
+            "jsx": true
+        },
+        "ecmaVersion": 2018,
+        "sourceType": "module"
+    },
+    "plugins": [
+        "react",
+        "jquery"
+    ],
+    "rules": {}
+}

WcaOnRails/package.json

@@ -23,6 +23,7 @@
     "classnames": "^2.2.6",
     "compression-webpack-plugin": "^3.1.0",
     "css-loader": "^3.4.2",
+    "easymde": "^2.9.0",
     "extract-text-webpack-plugin": "^3.0.2",
     "file-loader": "^4.2.0",
     "flag-icon-css": "viroulep/flag-icon-css#3.2.1-xk",
@@ -43,14 +44,20 @@
     "react-leaflet": "^2.6.3",
     "resolve-url-loader": "^3.1.1",
     "sass-loader": "^8.0.2",
-    "easymde": "^2.9.0",
     "style-loader": "^1.1.3",
     "webpack": "^4.42.0",
     "webpack-manifest-plugin": "^2.2.0",
     "webpack-merge": "^4.2.2",
     "whatwg-fetch": "^3.0.0"
   },
   "devDependencies": {
+    "eslint": "^6.8.0",
+    "eslint-config-airbnb": "^18.0.1",
+    "eslint-plugin-import": "^2.20.1",
+    "eslint-plugin-jquery": "^1.5.1",
+    "eslint-plugin-jsx-a11y": "^6.2.3",
+    "eslint-plugin-react": "^7.18.3",
+    "eslint-plugin-react-hooks": "^2.4.0",
     "jshint": "^2.11.0",
     "stylelint": "^12.0.1",
     "stylelint-config-recommended-scss": "^4.2.0",