2.typescript基础类型

喜欢ヅ旅行 2024-04-07 13:07 73阅读 0赞

## 数字类型 ##

let a: number = 0b1010; // 二进制
    let b: number = 0o744;    // 八进制
    let c: number = 6;    // 十进制
    let d: number = 0xf00d;    // 十六进制
    ---
    var a = 10; // 二进制
    var b = 484; // 八进制
    var c = 6; // 十进制
    var d = 0xf00d; // 十六进制

## 字符串类型 ##

let myname: string = "林扬生";
    let age: number = 24;
    let text: string = `${
           myname }今年${
           age}岁了！`;
    ---
    var myname = "林扬生";
    var age = 24;
    var text = "".concat(myname, "\u4ECA\u5E74").concat(age, "\u5C81\u4E86\uFF01");

## 布尔类型 ##

let flag:boolean=false;
    ---
    var flag = false;

## 数组类型 ##

let a: number[] = [1, 2, 3, 4, 5];
    let b: Array<number> = [1, 2, 3, 4, 5];
    let c: Array<any> = [1,"a", 3, [4],5];
    ---
    var a = [1, 2, 3, 4, 5];
    var b = [1, 2, 3, 4, 5];
    var c = [1, "a", 3, [4], 5];

## 元组类型 ##

let msg: [string, number];
    msg = ["林扬生", 24];   //正确
    msg = [1, 2];           //错误
    msg = [true, "林扬生"]; //错误

## 枚举类型 ##

如果标识符没有赋值，它的值就是下标。

enum color {
        
        blue,
        pink,
        red
    };
    let a: color = color.blue;
    ---
    var color;
    (function (color) {
        
        color[color["blue"] = 0] = "blue";
        color[color["pink"] = 1] = "pink";
        color[color["red"] = 2] = "red";
    })(color || (color = {
        }));
    ;
    var a = color.blue;//0
    var b = color.red;//2

如果标识符已经赋值，它的值就是被赋的值。

enum color {
        
        blue=100,
        pink=200,
        red="red"
    };
    
    let a: color = color.blue;
    let b: color = color.red;
    ---
    var color;
    (function (color) {
        
        color[color["blue"] = 100] = "blue";
        color[color["pink"] = 200] = "pink";
        color[color["red"] = 300] = "red";
    })(color || (color = {
        }));
    ;
    var a = color.pink;//200
    var b = color.red;//red

如果标识符没有赋值，它的值就是下标，如果从中间突然指定了一个值，那么它之后的值都会从当前值开始重新计算。

enum color {
        
        blue,
        pink=100,
        red
    };
    let a: color = color.red;
    ---
    var color;
    (function (color) {
        
        color[color["blue"] = 0] = "blue";
        color[color["pink"] = 100] = "pink";
        color[color["red"] = 101] = "red";
    })(color || (color = {
        }));
    ;
    var a = color.red;//101

## null类型 ##

let n: null = null;

## undefined类型 ##

let u: undefined = undefined;

## any类型 ##

enum color {
        
        blue,
        pink,
        red
    };
    let flag: any = true;//布尔型
    let num: any = 123;//数字型
    let str: any = 'Hello,TypeScript';//字符型
    let arr: any = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0];//数组型
    let tuple: any = [10086, 'Nick'];//元组型
    let e: any = color.pink;//枚举型
    let n: any = null;//null型
    let u: any = undefined;//undefined型
    ---
    var color;
    (function (color) {
        
        color[color["blue"] = 0] = "blue";
        color[color["pink"] = 1] = "pink";
        color[color["red"] = 2] = "red";
    })(color || (color = {
        }));
    ;
    var flag = true; //布尔型
    var num = 123; //数字型
    var str = 'Hello,TypeScript'; //字符型
    var arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]; //数组型
    var tuple = [10086, 'Nick']; //元组型
    var e = color.pink; //枚举型
    var n = null; //null型
    var u = undefined; //undefined型

## void类型 ##

function success(): void {
        
        console.log('不需要返回值');
    }
    ---
    function success() {
        
        console.log('不需要返回值');
    }

## never类型 ##

function error(): never {
        
        throw new Error('抛出错误了');
    }
    ---
    function error(){
        
        throw new Error('抛出错误了');
    }

## 组合类型 ##

let num: number | null | undefined;
    num = 3;
    num = null;
    num = undefined;-
    ---
    var num;
    num = 3;
    num = null;
    num = undefined;