tooling: add 'npm run lint' (and config)

.jshintrc

@@ -0,0 +1,23 @@
+{
+  "browser": true,
+  "node": true,
+  "esversion": 11,
+  "curly": true,
+  "sub": true,
+
+  "bitwise": true,
+  "eqeqeq": true,
+  "forin": true,
+  "freeze": true,
+  "immed": true,
+  "latedef": "nofunc",
+  "nonbsp": true,
+  "nonew": true,
+  "plusplus": true,
+  "undef": true,
+  "unused": "vars",
+  "strict": true,
+  "maxdepth": 4,
+  "maxstatements": 100,
+  "maxcomplexity": 20
+}

package.json

@@ -5,7 +5,8 @@
   "description": "webinstall script repository",
   "main": "_webi/",
   "scripts": {
-    "prettier": "npx prettier@2 -w '**/*.{js,md,html}'",
+    "prettier": "npx prettier@2.x -w '**/*.{js,md,html}'",
+    "lint": "npx jshint@2.x -c ./.jshintrc */*.js",
     "shfmt": "shfmt -w -i 4 -sr -s ./",
     "test": "node _webi/test.js ./node/"
   },