30-seconds-of-code/snippets/isDeepFrozen.md

title, tags

title	tags
isDeepFrozen	object,recursion,intermediate

Checks if an object is deeply frozen

Use recursion. Use Object.isFrozen() on the given object. Use Object.keys(), Array.prototype.every() to check that all keys are either deeply frozen objects or non-object values.

const isDeepFrozen = obj =>
  Object.isFrozen(obj) &&
  Object.keys(obj).every(
    prop => typeof obj[prop] !== 'object' || isDeepFrozen(obj[prop])
  );

const x = Object.freeze({ a: 1 });
const y = Object.freeze({ b: { c: 2 } });
isDeepFrozen(x); // true
isDeepFrozen(y); // false