Omit

introduction#

Implement the built-in Omit<T, K> generic without using it.

Constructs a type by picking all properties from T and then removing K

For example

ts
interface Todo {
  title: string
  description: string
  completed: boolean
}
type TodoPreview = MyOmit<Todo, 'description' | 'title'>
const todo: TodoPreview = {
  completed: false,
}

ts
interface Todo {
  title: string
  description: string
  completed: boolean
}
type TodoPreview = MyOmit<Todo, 'description' | 'title'>
const todo: TodoPreview = {
  completed: false,
}

View on GitHub

start point#

ts
/* _____________ Your Code Here _____________ */
type MyOmit<T, K> = any
 
/* _____________ Test Cases _____________ */
type cases = [
  Expect<Equal<Expected1, MyOmit<Todo, 'description'>>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.  Expect<Equal<Expected2, MyOmit<Todo, 'description' | 'completed'>>>
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.]
 
interface Todo {
  title: string
  description: string
  completed: boolean
}
 
interface Expected1 {
  title: string
  completed: boolean
}
 
interface Expected2 {
  title: string
}Try

ts
/* _____________ Your Code Here _____________ */
type MyOmit<T, K> = any
 
/* _____________ Test Cases _____________ */
type cases = [
  Expect<Equal<Expected1, MyOmit<Todo, 'description'>>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.  Expect<Equal<Expected2, MyOmit<Todo, 'description' | 'completed'>>>
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.]
 
interface Todo {
  title: string
  description: string
  completed: boolean
}
 
interface Expected1 {
  title: string
  completed: boolean
}
 
interface Expected2 {
  title: string
}Try

take the challenge

my solutions#

Spoiler warning // Click to reveal answer

ts
type MyOmit<T , K extends string | number | symbol> = {
  [Key in Exclude<keyof T, K>]: T[Key]
}Try

ts
type MyOmit<T , K extends string | number | symbol> = {
  [Key in Exclude<keyof T, K>]: T[Key]
}Try

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