Prevent var usage before definition

This will aid migration to let/const in future

.eslintrc

@@ -12,10 +12,15 @@
   },
   "rules": {
     "block-scoped-var": "error",
+    "eqeqeq": "error",
     "no-console": [
       "error",
       { allow: ["warn", "error"] },
     ],
+    "no-use-before-define": [
+      "error",
+      {"functions": false},
+    ],
     "strict": ["error", "safe"],
   },
   "parserOptions": {