Rule proposal: Prevent Object.values(...) usage with Map

[MadLittleMods]

Before You File a Proposal Please Confirm You Have Done The Following...

• I have searched for related issues and found none that match my proposal.
• I have searched the current rule list and found no rules that match my proposal.
• I have read the FAQ and my problem is not listed.

My proposal is suitable for this project

• My proposal specifically checks TypeScript syntax, or it proposes a check that requires type information to be accurate.
• My proposal is not a "formatting rule"; meaning it does not just enforce how code is formatted (whitespace, brace placement, etc).
• I believe my proposal would be useful to the broader TypeScript community (meaning it is not a niche proposal).

Description

Using Object.values(...), Object.keys(...), Object.entries(...) with a Map object is a foot-gun because it will return empty [] regardless of the map contents and is most likely a mistake. These sorts of mistakes are easy to get into during refactors. This issue is spawning from a real-life refactor mistake -> element-hq/element-web#24995 (comment)

Related StackOverflow question: https://stackoverflow.com/questions/72315392/how-to-prevent-the-mistake-of-calling-object-values-on-a-map

As @bergus mentions from the SO question, it's possible to extend Map to make a subclass that returns something with the object utilities but this seems a lot more niche compared to the big problem of running them on base Map objects. AFAICT, it's not possible to use TypeScript on its own to catch this sort of thing because practically everything inherits from Object and function arguments in TypeScript are contravariant (accepts supertypes but doesn't accept subtypes).

Fail Cases

const map = new Map([[ 1, 'one' ],[ 2, 'two' ]]);

// Rule would error for each of these usages, as using these object utilities
// on a Map will just return empty results and is probably a mistake
Object.keys(map); // -> []
Object.values(map); // -> []
Object.entries(map); // -> []

Pass Cases

const myObject = { 1: 'one', 2: 'two' };
Object.keys(myObject); // -> ['1', '2']
Object.values(myObject); // -> ['one', 'two']
Object.entries(myObject); // -> [[ 1, 'one' ],[ 2, 'two' ]]

const map = new Map([[ 1, 'one' ],[ 2, 'two' ]]);
map.keys(); // -> ['1', '2']
map.values(); // -> ['one', 'two']
map.entries(); // -> [[ 1, 'one' ],[ 2, 'two' ]]

Additional Info

No response

[Josh-Cena]

This presents an interesting intersection with no-misused-in proposed in #5677. They both deal with attempting to use maps/sets as if they have object properties. I wonder how we could make the one proposed here more generalizable.

[bradzacher]

Heh this request reminded me of that exact same issue! Yeah there's something interesting here because they're all related but also distinct problem sets.

Maybe a big rule like no-misused-object-likes would be a good thing?