001基本类型

// 基本数据类型
const num: number = 111;
const str: string = ‘shasng‘;
const bool: boolean = true;
const define: undefined = undefined;

// 引用数据类型
const arr: number[] = [1, 2, 4];

//元组 Tuple

const tupleArr: [string, number, boolean] = [‘shang‘,1, true];

// 枚举
// enum Color {Red, Green, Blue}
// let c: Color = Color.Green;

enum Color {Red = 1, Green, Blue}
let colorName: string = Color[2];

// Any

let n: any = 1235;
n.toFixed(2);

let t: Object = 1235;
t.toString();

const arr1: any[]  = [1,"shsghhg", false]

// 默认情况下null和undefined是所有类型的子类型。 就是说你可以把 null和undefined赋值给number类型的变量。

//类型断言
const x: any = [1,2,3];
const len: number = (x as string).length;