TS/part1/01.ts

let a: number;
a = 4;

// &表示同时
let j: {name: string} & {age: number};
j = {name: 'ddd',age: 33};

// 类型别名
let k: 1 | 2 | 3;

type myType = 1 | 2 | 3;
let m: myType;