Options bag option names

[peetklecha]

This proposal will introduce an options bag to JSON.parse with (for now) two flags: One which freezes objects and one which makes plain (non-array) objects have a null prototype. We are committed to flags whose default value is false and where the false behavior aligns with current JSON.parse behavior without a reviver.

What should the option bag property names be? Per #8 it might be helpful for compat if the names are not extremely terse.

My current preferences therefore are

freezeObjects -- something as terse as frozen or freeze increases likelihood of web compat issues. but maybe this is overthinking
nullPrototype -- technically doesn't quite capture the fact that only non-array objects will get a null prototype, but that seems hard to capture without getting ridiculous.

[ljharb]

Since JSON.parse has never had an options bag, I think the web compat risk of option names is effectively zero.

[acutmore]

I agree that the web compat risk is effectively zero. The most likely pattern where a non function is being passed as the 2nd argument is arr.map(JSON.parse), where the 2nd argument would be a number - which we would ignore.

If code was doing: JSON.parse(str, Object), where the 2nd argument does have a .freeze property but is also a function, so again we would ignore from an options bag perspective.

So I would be comfortable pursuing JSON.parse(str, { freeze: true }).

As per #6 (comment) we could say that freeze: true implies a null prototype for JSON objects to keep the recommended approach the most brief.

Options Bag	Frozen objects & arrays	null proto for objects (not arrays)
undefined	❌	❌
{}	❌	❌
{ freeze: true }	✅	✅
{ freeze: false }	❌	❌
{ preferNullPrototype: true }	❌	✅
{ preferNullPrototype: false }	❌	❌
{ freeze: true, preferNullPrototype: false }	✅	❌
{ freeze: true, preferNullPrototype: true }	✅	✅
{ freeze: false, preferNullPrototype: true }	❌	✅
{ freeze: false, preferNullPrototype: false }	❌	❌