二、Typescript5-TS数据类型

数据类型

• JS的所有类型
• 元组：tuple
• 枚举：enum
• 特殊类型：void、never、any、unknown

JS的类型

基础数据类型

• number
• string
• boolean
• null
• undefined
• symbol
• bigint

let num: number = 2;
let str: string = "hello".toString();
let bool: boolean = true;
let nul: null = null;
let und: undefined = undefined;
let sym: symbol = Symbol("sym");

引用数据类型

• object
• array
• function
• date
• regexp
• map
• set
• weakmap
• weakset

let obj: object = {}; // 不建议使用
let array: string[] = [];
let array1: Array<string> = [];
let date: Date = new Date();
let regexp: RegExp = /hello/;
let map: Map<string, number> = new Map();
let weakmap: WeakMap<{name: string}, number> = new WeakMap();
let set: Set<number> = new Set();
let weakset: WeakSet<{name: string}> = new WeakSet();

元组：tuple

let tuple: [number, string, boolean] = [110, "hello", true];

枚举：enum

enum Gender {
  Man = "man",
  Woman = "woman",
}
let gen: Gender = Gender.Man;

特殊类型：void、never、any、unknown

any：告诉编译器放弃ts静态检测，不安全，不用

unknown：定义该变量的时候不知道是什么类型，可以随意给该变量赋值，但是不能操作该变量，只有当该变量的类型确定时，可以操作

let unknownType: unknown = 123;
unknownType = "123"; 
if(typeof unknownType === "string"){
  console.log(unknownType.toLowerCase());
}

void：没有返回值，一般用于定义函数

function fn():void{}

never：永远无法获得的值

let neverType: never = (() => {
  throw new Error("error");
})();