Set.has should accept any type

[ktmud]

Suggestion

Currently if you do

const mySet = new Set(['foo'] as const])
mySet.has('bar')

Line 2 throws an Argument of type '"bar"' is not assignable to parameter of type '"foo"' error.

However, set.has(...) is meant to detect whether an element is in the set, therefore by definition it should be able to accept arguments that are not in the set---in which case, it just returns false.

It seems the fix is simply replace

TypeScript/lib/lib.es2015.collection.d.ts

Line 63 in 69cc9ba

has(value: T): boolean;

with

    has(value: any): boolean;

🔍 Search Terms

set, has, dom, lib, any, type, const

✅ Viability Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

⭐ Suggestion

Allow set.has(...) to accept any arguments that are not in the set.

📃 Motivating Example

N/A

💻 Use Cases

N/A

[IllusionMH]

Looks like a duplicate of #42641

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.