Add type predicate to Object.is

Search Terms

object.is

type predicate

Suggestion

When a is b, a and b has to same type, so I suggest adding a few generic overloads with type predicates

interface ObjectConstructor {
  is<A, B extends A> (a: A, b: B): a is B
  is<A extends B, B> (a: A, b: B): b is A
  is (a: any, b: any): boolean
}

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, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

Der Issue schlägt generische Type-Predicate-Overloads für Object.is vor, nennt aber keine Quelldateien oder Tests. Beginne damit, die bestehende Object.is-Deklaration und zugehörige Type-Predicate-Tests zu finden, und bestimme dann, ob die vorgeschlagenen Overloads stichhaltig sind und welche Testabdeckung das beabsichtigte Narrowing-Verhalten demonstrieren würde.