function greeter1 (person: string) {
  return 'Hello, ' + person
}

let userr = 'Yee'

console.log(greeter1(userr))

//person:string 类型注释
/**
 使用接口来描述一个拥有 firstName 和 lastName 字段的对象
 interface Person {
  firstName: string
  lastName: string
}

function greeter (person: Person) {
  return 'Hello, ' + person.firstName + ' ' + person.lastName
}

let user = {
  firstName: 'Yee',
  lastName: 'Huang'
}

console.log(greeter(user))
 */