Add frozenSet

snippets/frozenSet.md

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+---
+title: frozenSet
+tags: array,intermediate
+---
+
+Creates a frozen `Set` object.
+
+- Use the `new Set()` constructor to create a new `Set` object from `iterable`.
+- Set the `add`, `delete` and `clear` methods of the newly created object to `undefined`, so that they cannot be used, practically freezing the object.
+
+```js
+const frozenSet = iterable => {
+  const s = new Set(iterable);
+  s.add = undefined;
+  s.delete = undefined;
+  s.clear = undefined;
+  return s;
+};
+```
+
+```js
+frozenSet([1, 2, 3, 1, 2]); 
+// Set { 1, 2, 3, add: undefined, delete: undefined, clear: undefined }
+```