Pick<T, K> 从 T 中挑选部分属性构成新类型

interface Person {name: string;age: number;email?: string;
}type PickedPerson = Pick<Person, "name" | "age">; // { name: string; age: number }const person: PickedPerson = {age: 20,name: "Tom",
};

Partial：将类型的所有属性变为可选

interface IProps {name: string;age: number;sex: "男" | "女";job?: string;
}type Person2 = Partial<IProps>; // { name?: string; age?: number; sex?: "男" | "女"; job?: string }const person2: Person2 = {name: "Tom",sex: "男",
};

Required：将类型的属性变为必选。

interface IProps {name: string;age: number;sex: "男" | "女";job?: string;
}type Person3 = Required<IProps>; // { name: string; age: number; sex: "男" | "女"; job: string }const person3: Person3 = {name: "Tom",age: 20,sex: "男",job: "程序员",
};

Omit<T, K>：从 T 中移除部分属性构成新类型。

interface IProps {name: string;age: number;sex: "男" | "女";job?: string;
}type Person6 = Omit<IProps, "sex" | "name">; // { age: number; job?: string }const person6 : Person6 = {age: 20,job: "程序员",
}

Readonly：将类型的属性设为只读。

interface IProps {name: string;age: number;sex: "男" | "女";job?: string;
}type Person4 = Readonly<IProps>;const person4: Person4 = {name: "Tom",age: 20,sex: '男',
}// person4.name = "Jerry"; // 会报错，因为name是只读的

Record<string | number | symbol，any>

Record<string | number | symbol，any> 是一个类型工具，用于创建一个对象类型，其中键的类型可以选三种 ，值的类型可以任意规定

interface IProps {name: string;age: number;sex: "男" | "女";job?: string;
}type Person = Pick<IProps, "name" | "age">;const person5: Record<string, Person> = {Tom: {name: "Tom",age: 20,},Jerry: {name: "Jerry",age: 22,},
}

类型推断

ReturnType 是返回函数的返回值的类型
Parameters 是返回参数的类型

type Func = (x: number, y: string) => boolean;
type ReturnTypeOfFunc = ReturnType<Func>; // boolean
type ParametersOfFunc = Parameters<Func>; // [number, string]

数组的不可变性 (ReadonlyArray)

ReadonlyArray 是 readonly 在数组中的一种特例。与普通数组不同，ReadonlyArray 禁止使用会修改数组的方法（例如 push、pop 等），从而确保数组内容不会被改变。

const numbers: ReadonlyArray<number> = [1, 2, 3];// numbers.push(4); // 错误：ReadonlyArray 不允许修改数组内容

深度不可变 DeepReadonly

仅将嵌套对象设为不可变，而让顶层的普通属性保持可变状态

type DeepReadonly<T> = {[K in keyof T]: T[K] extends object ? Readonly<T[K]> : T[K];};interface PersonA {name: string;address: { city: string; zip: string };}const person7: DeepReadonly<PersonA> = {name: "Alice",address: { city: "New York", zip: "10001" },};person7.name = "Bob"; // person7.address.city = "Boston" // Error