TS

// 定义变量
let age: number = 25
let username: string = "Alice"
let isAdmin: boolean = true


// 数组与对象
let numbers: number[] = [1, 2, 3]
let user: { id: number; name: string } = { id: 1, name: "Tom" }


//接口
interface User {
  id: number
  name: string
  age?: number   // 可选属性
}

const u: User = { id: 1, name: "Lucy" }


// 类
class Person {
  constructor(public name: string, private age: number) {}

  greet() {
    console.log(`Hi, I'm ${this.name}`)
  }
}

const p = new Person("Jack", 20)
p.greet()



// 范型
function identity<T>(arg: T): T {
  return arg
}

let output = identity<string>("Hello")