Implement deep clone for complex objects
Company: Apple
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
Implement a deep-clone function for nested objects in JavaScript (or a language of your choice) without using JSON serialization or third-party libraries. Requirements:
- Correctly copy primitives, plain objects, arrays, Maps, Sets, Dates, and RegExps.
- Preserve object prototypes and property descriptors (writable, enumerable, configurable) when possible.
- Handle circular references and shared substructures so identical references remain shared after cloning.
- Support symbol keys and non-enumerable properties.
- Do not clone functions; keep function references as-is.
- Discuss time and space complexity, recursion vs. iteration, and stack-safety for very deep graphs.
- Provide tests for edge cases such as self-referential objects, sparse arrays, NaN/Infinity/-0, typed arrays, and large object graphs.
Quick Answer: This question evaluates mastery of deep object cloning, reference and memory management, and knowledge of language runtime details such as prototypes, property descriptors, symbol-keyed and non-enumerable properties, and built-in types like Maps, Sets, Dates, RegExps, and typed arrays.