基础类型

1. 基础类型演示

let age: number = 18;

let hello: string = "hello";

let isLoading: boolean = false;

let u: undefined = undefined;

let n: null = null;

let s: symbol = Symbol();

// 数组类型
let nums1: number[] = [1, 2, 3];
let nums2: Array<number> = [1, 2, 3];

// 联合类型
let arr: (string | number)[] = [1, "a", 3];

// 类型别名 作为类型注解
type StringNumArr = (string | number)[];
let arr1: StringNumArr = [1, "a", 2];
let arr2: StringNumArr = [1, "b", 3];