Deep Freeze Object Javascript

deepFreezeObject.js

// Object.freeze() will not freeze nested objects. The function below 
// will freeze all nested objects for immutability.

let isObject = (val) => val && typeof val === 'object';
function deepFreezeObject(obj) {
  if(isObject(obj) && !Object.isFrozen(obj)){ 
    // Recusively call until all child objects are frozen
    Object.keys(obj).forEach(name => deepFreezeObject(obj[name]));
    Object.freeze(obj);
  }
  return obj;
}