TypeStript 入门 - 08：自定义类型

Diff：实现

let person1 = {
 name: 'pt',
 age: 11,
 address: 'sz'
}

let person2 = {
 address: 'sz',
}

//! 1.Diff：实现
type Diff<T extends Object, K extends Object> = Omit<T, keyof K>
//! 其实就是将persion1中把persion2中的类型忽略，得到剩余的类型
type DiffPerson = Diff<typeof person1, typeof person2>
/*
type DiffPerson = {
 name: string;
 age: number;
}
 */

InterSection: 交集

let person1 = {
 name: 'pt',
 age: 11,
 address: 'sz'
}

let person2 = {
 address: 'sz',
}

//! 2.InterSection: 交集
//! pick 选取 然后extract T和K 都存在的，就是交集的部分
type InterSection<T extends Object, K extends Object> = Pick<T, Extract<keyof T, keyof K>>
type InterSectionPerson = InterSection<typeof person1, typeof person2>
/* 
type InterSectionPerson = {
  address: string;
}
 */

Overwrite: 属性覆盖

//注意：OldProps 与 NewProps age 类型分别为number 和string，类型是不同的
 type OldProps = { name: string, age: number, visible: boolean };
 type NewProps = { age: string, other: string };

 type InterSection<T extends Object, K extends Object> = Pick<T, Extract<keyof T, keyof K>>
 //1. 获取交集部分，也就是age，让NewProps 覆盖 OldProps 属性类型，age 变成string 类型
 type InterSectionProps = InterSection<NewProps, OldProps>;

 type Diff<T extends Object, K extends Object> = Omit<T, keyof K>
 //2. 获取不同部分，也就是age,visible
 type DiffProps = Diff<OldProps, NewProps>;//Diff 是从OldProps 类型中忽略掉NewProps 剩余的类型部分

 //3. 组合DiffProps与InterSectionProps，然后pick 提取所有属性就是最终的结果
 type ComposeProps = DiffProps & InterSectionProps;
 //! 最终ReplaceProps1 与 ReplaceProps2 类型一致
 type ReplaceProps1 = Pick<ComposeProps, keyof ComposeProps>;

 type Overwrite<T extends Object, K extends Object, I = Diff<T, K> & InterSection<K, T>> = Pick<I, keyof I>
 //! 3.Overwrite: 属性覆盖
 type ReplaceProps2 = Overwrite<OldProps, NewProps>
 /* 
 type ReplaceProps2 = {
    name: string;
    age: string;
    visible: boolean;
 }
 */

Merge对象合并

//注意：OldProps 与 NewProps age 类型分别为number 和string，类型是不同的
type OldProps = { name: string, age: number, visible: boolean };
type NewProps = { age: string, other: string };

type Compose<A extends any> = { [K in keyof A]: A[K] };

//! 说明：OldProps 中忽略掉NewProps 的部分，然后再&组合NewProps 部分，得到的就是合并后的结果
type Merge<T, K> = Compose<Omit<T, keyof K> & K>;
//! 4.Merge: 属性合并
type MergeObj = Merge<OldProps, NewProps>
/* 
type MergeObj = {
 name: string;
 visible: boolean;
 age: string;
 other: string;
}
*/