fix code styling

.eslintrc.json

@@ -0,0 +1,17 @@
+{
+  "env": {
+    "browser": true,
+    "commonjs": true,
+    "es2021": true
+  },
+  "extends": "eslint:recommended",
+  "parserOptions": {
+    "ecmaVersion": "latest"
+  },
+  "rules": {
+    "indent": ["error", 2],
+    "linebreak-style": ["error", "unix"],
+    "quotes": ["error", "double"],
+    "semi": ["error", "always"]
+  }
+}