TypeScript: Emulate Omit built-in

Solution

type MyOmit<T, K extends keyof T> = {
  [P in keyof T as P extends K ? never : P]: T[P]
}

/* _____________ Test Cases _____________ */
import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
  Expect<Equal<Expected1, MyOmit<Todo, 'description'>>>,
  Expect<Equal<Expected2, MyOmit<Todo, 'description' | 'completed'>>>,
]

// @ts-expect-error
type error = MyOmit<Todo, 'description' | 'invalid'>

interface Todo {
  title: string
  description: string
  completed: boolean
}

interface Expected1 {
  title: string
  completed: boolean
}

interface Expected2 {
  title: string
}

TypeScript playground

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