The solutions presented fail if one of the values in obj is a function. E.g., JSON.parse(JSON.stringify({foo:x=>x})) returns {}.

It's not intuitively obvious what the "correct" solution ought to be. If cloner is a deep-cloning function, and f is a function, which of the following should be true?

1. cloner(f) === f?

2. For all ...args, cloner(f)(...args) === f(...args)?

3. For all ...args, cloner(f)(...args) === cloner(f(...args))?

4. For all ...args, cloner(f)(...args) === f(...args.map(cloner))?

5. For all ...args, cloner(f)(...args) === cloner(f(...args.map(cloner)))?

6. Something else entirely?