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TS内置类型总结

news 2025/8/5 14:07:32

typeof 取对象身上的类型

const person = {name: '',job: '',age:18
}
type p = typeof person
->>
type p = {name: string;job: string;age: number;
}

keyof取一个类型的属性明作为一个联合类型

const person = {name: '',job: '',age: 18
}
type p = typeof person
type k = keyof p 
--》》
type k = "name" | "job" | "age"

Partial将传入的泛型中每个属性都变成可选属性

源码
type Par<T> = {[P in keyof T]?:T[P]
}interface person  {name: string,job: string,age: number
}
type a = Partial<person>
-》》
type a = {name?: string | undefined;job?: string | undefined;age?: number | undefined;
}

Pick在传入泛型T中筛选出指定属性K的类型

源码
type Pick<T,K extends keyof T> = {[P in K]:T[P]
}interface person {name: string,job: string,age: number
}
type pick = Pick<person, 'age'>
——》》
interface person {name: string,job: string,age: number
}

Record将泛型K作为属性名（K可是联合类型） T作为属性类型

type Record<K extends keyof any,T> = {[P in K]:T
}
keyof any = ->>> string | number | symbolinterface person {name: string,job: string,age: number
}
type human = 'name' | 'job'
type record = Record<human, person>
type record = {name: person;job: person;
}

Readonly将传入的泛型全部属性变成只读

type Readonly<T> = {readonly [P in keyof T]:T[P]
}interface person {name: string,job: string,age: number
}
type readonly = Readonly<person>
--->
type readonly = {readonly name: string;readonly job: string;readonly age: number;
}