add linter

.eslintrc.json

@@ -0,0 +1,53 @@
+{
+    "extends": "eslint:recommended",
+    "env": {
+        "node": true,
+        "es6": true
+    },
+    "parserOptions": {
+        "ecmaVersion": 2021
+    },
+    "rules": {
+        "arrow-spacing": ["warn", { "before": true, "after": true }],
+        "brace-style": ["error", "1tbs", { "allowSingleLine": true }],
+        "comma-dangle": ["error", "always-multiline"],
+        "comma-spacing": "error",
+        "comma-style": "error",
+        "curly": ["error", "multi-line", "consistent"],
+        "dot-location": ["error", "property"],
+        "handle-callback-err": "off",
+        "keyword-spacing": "error",
+        "max-nested-callbacks": ["error", { "max": 4 }],
+        "max-statements-per-line": ["error", { "max": 2 }],
+        "no-console": "off",
+        "no-empty-function": "error",
+        "no-floating-decimal": "error",
+        "no-inline-comments": "error",
+        "no-lonely-if": "error",
+        "no-multi-spaces": "error",
+        "no-multiple-empty-lines": [
+            "error",
+            { "max": 2, "maxEOF": 1, "maxBOF": 0 }
+        ],
+        "no-shadow": ["error", { "allow": ["err", "resolve", "reject"] }],
+        "no-trailing-spaces": ["error"],
+        "no-var": "error",
+        "object-curly-spacing": ["error", "always"],
+        "prefer-const": "error",
+        "quotes": ["error", "single"],
+        "space-before-blocks": "error",
+        "space-before-function-paren": [
+            "error",
+            {
+                "anonymous": "never",
+                "named": "never",
+                "asyncArrow": "always"
+            }
+        ],
+        "space-in-parens": "error",
+        "space-infix-ops": "error",
+        "space-unary-ops": "error",
+        "spaced-comment": "error",
+        "yoda": "error"
+    }
+}