TypeScript里的工具类型Partial的用法
TypeScript里的工具类型Partial的用法
Jerry Wang
发布于 2020-12-17 15:33:37
发布于 2020-12-17 15:33:37
在SAP Spartacus的源代码里我们可以观察到很多Partial的使用场景：
Partial 可以快速把某个接口类型中定义的属性变成可选的(Optional)：
interface People {
age: number;
name: string;
}
const Jerry:People = {
age: 10,
name: 'Jerry'
};
const Tom: People = {
name: 'Tom'
}上述代码会发生编译时错误：
1.ts:11:7 - error TS2741: Property ‘age’ is missing in type ‘{ name: string; }’ but required in type ‘People’.
解决方法：
interface People {
age: number;
name: string;
}
const Jerry:People = {
age: 10,
name: 'Jerry'
};
type AnonymousPeople = Partial<People>;
const tom:AnonymousPeople = {
name: 'Tom'
};编译之后：
var Jerry = {
age: 10,
name: 'Jerry'
};
var tom = {
name: 'Tom'
};这个工具类型的实现毫无神奇之处：
type Partial<T> = {
[P in keyof T]?: T[P];
};
我们完全可以自行实现：
interface People {
age: number;
name: string;
}
const Jerry:People = {
age: 10,
name: 'Jerry'
};
type JerryPartial<T> = {
[P in keyof T]?: T[P];
};
type AnonymousPeople = JerryPartial<People>;
const tom:AnonymousPeople = {
name: 'Tom'
};本文参与 腾讯云自媒体分享计划，分享自作者个人站点/博客。
原始发表：2020-11-30 ，如有侵权请联系 cloudcommunity@tencent.com 删除
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