style: Add eslint

.eslintrc.js

@@ -0,0 +1,19 @@
+module.exports = {
+    "env": {
+        "browser": true,
+        "commonjs": true,
+        "es6": true,
+        "node": true
+    },
+    "extends": "eslint:recommended",
+    "globals": {
+        "Atomics": "readonly",
+        "SharedArrayBuffer": "readonly"
+    },
+    "parserOptions": {
+        "ecmaVersion": 2018
+    },
+    "rules": {
+        "one-var": ["warn", { "initialized": "never" }]
+    }
+}

package.json

@@ -37,6 +37,7 @@
         "@node-minify/core": "^4.0.5",
         "@node-minify/uglify-es": "^4.0.5",
         "cypress": "^3.3.1",
+        "eslint": "^5.16.0",
         "http-server": "^0.11.1"
     },
     "engines": {