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Mutable

介绍​

实现一个通用的类型 Mutable<T>，使类型 T 的全部属性可变（非只读）。

ts
interface Todo {
  readonly title: string
  readonly description: string
  readonly completed: boolean
}
type MutableTodo = Mutable<Todo> // { title: string; description: string; completed: boolean; }
ts
interface Todo {
  readonly title: string
  readonly description: string
  readonly completed: boolean
}
type MutableTodo = Mutable<Todo> // { title: string; description: string; completed: boolean; }
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起点​

ts
/* _____________ Your Code Here _____________ */
 
type Mutable<T> = any
 
/* _____________ Test Cases _____________ */
 
interface Todo1 {
  title: string
  description: string
  completed: boolean
  meta: {
    author: string
  }
}
 
type List = [1, 2, 3]
 
type cases = [
  Expect<Equal<Mutable<Readonly<Todo1>>, Todo1>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Mutable<Readonly<List>>, List>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
]
 
ts
/* _____________ Your Code Here _____________ */
 
type Mutable<T> = any
 
/* _____________ Test Cases _____________ */
 
interface Todo1 {
  title: string
  description: string
  completed: boolean
  meta: {
    author: string
  }
}
 
type List = [1, 2, 3]
 
type cases = [
  Expect<Equal<Mutable<Readonly<Todo1>>, Todo1>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
  Expect<Equal<Mutable<Readonly<List>>, List>>,
Type 'false' does not satisfy the constraint 'true'.2344Type 'false' does not satisfy the constraint 'true'.
]
 
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解决方案​

Spoiler warning // Click to reveal answer
ts
// most popular
 
type Mutable<T> = {
  -readonly [K in keyof T]:T[K]
}
 
ts
// most popular
 
type Mutable<T> = {
  -readonly [K in keyof T]:T[K]
}
 
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