对象类型

定义对象（属性）类型

const p1: { name: string; age: number; say(): void; greet(name: string): void } = {
  name: 'foo',
  age: 18,
  say() {},
  greet(name) {},
}

// ? 可选属性
const p2: {
  name: string
  age?: number
  say(): void
  greet?(name: string): void
} = {
  name: 'foo',
  say() {},
}