实现 Partial

Partial 作用是将传入的属性变为可选项.

interface Person {
  name: string;
  age: number;
}

function updatePerson(person: Person, fieldsToUpdate: Partial<Person>): Person {
  return { ...person, ...fieldsToUpdate };
}

const person: Person = {
  name: 'Alice',
  age: 24
};

const updatedPerson = updatePerson(person, { age: 25 });

Partial 实现原理

type Partial<T> = {
  [K in keyof T]?: T[K]
}