数组和元组

//数组
const arr: (string | number)[] = ['123', 1, 56]

const arr2: string[] = ['11', '22', '33']//数组里面一个类型的时候  可以不用写括号直接写类型就好

const arr3: undefined[] = [undefined]

//类型别名
type user = { name: string, age: number }

class user2 {
  name: string;
  age: number
}

const arr4: user[] = [
  {
    name: '123',
    age: 18
  }
]

const arr5: user2[] = [ //这样写也是不报错的  ts不会强制要求必须是 new user2() user2()里面也是含有name和age属性的 class可以和类型穿插使用
  {
    name: '123',
    age: 18
  }
]

//元祖:数量，个数有限，每一项的的类型又是固定的数组  这样一个特殊的数组就是元组
const arr6: [string, number, number] = ['123', 456, 789]

//csv

const arr7: [string, number, number][] = [
  ['123', 456, 789],
  ['123', 456, 789],
  ['123', 456, 789],
]