ancora su Typescript...

suddiviso i ts dai html e scss

src/validation/duplicate.ts

@@ -0,0 +1,23 @@
+type t = string | number;
+type fn = () => t[];
+
+export function duplicate(matches: t[] | fn, ignoreCase: boolean = false) {
+  if (Array.isArray(matches)) return factory(matches, ignoreCase);
+
+  return value => {
+    let cb = factory(matches(), ignoreCase);
+    return cb(value);
+  };
+}
+
+function factory(values: t[], ignoreCase: boolean) {
+  return value => {
+    if (value === undefined || value === null || values.length === 0)
+      return true;
+    else{
+      let flags = ignoreCase ? "i" : "";
+      let exp = new RegExp(`^(${value})$`, flags);
+      return values.find(o => exp.test(o.toString())) === undefined;
+    }
+  };
+}