00018-medium-merge

[yunliuyan]

Merge

by ZYSzys @ZYSzys

   

将两个类型合并成一个类型，第二个类型的键会覆盖第一个类型的键。

例如

type foo = {
  name: string;
  age: string;
}

type coo = {
  age: number;
  sex: string
}

type Result = Merge<foo,coo>; // expected to be {name: string, age: number, sex: string}

[yunliuyan]

思路

key 遍历为foo,coo的合集

代码实现

type Merge<T, U> = {
  [key in keyof T | keyof U]: key extends keyof U ? U[key] : key extends keyof T ? T[key] : never;
} 

type Result = Merge<foo,coo>; // expected to be {name: string, age: number, sex: string}

[Janice-Fan]

type Merge<T extends Object, P extends Object> =  {
    [k in keyof T | keyof P]: k extends keyof P ? P[k] : k extends keyof T ? T[k] : never;
}

type foo = {
    name: string;
    age: string;
}

type coo = {
    age: number;
    sex: string
}

type Result = Merge<foo,coo>; // expected to be {name: string, age: number, sex: string}

[liangchengv]

type Merge<T, U> = {
  [K in keyof T | keyof U]: K extends keyof U ? U[K] : K extends keyof T ? T[K] : never;
};

type foo = {
  name: string;
  age: string;
}

type coo = {
  age: number;
  sex: string
}

type Result = Merge<foo,coo>; 

[wudu8]

type MyMerge<T, U> = {
  [key in keyof T | keyof U]: key extends keyof U ? U[key] : key extends keyof T ? T[key] : never;
} 

type foo = {
  name: string;
  age: string;
}

type coo = {
  age: number;
  sex: string
}

type mergeResult = MyMerge<foo,coo>; // expected to be {name: string, age: number, sex: string}