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  • 第三章 Typescript 基本数据类型

    Typescript 基本数据类型

    一、基本数据类型

    • Boolean
    • Number
    • String
    • Array
    • Tuple
    • Enum
    • Any
    • Void
    • Null 和 Undefined
    • Never

    二、代码示例

    //布尔值
    let isDone: boolean = false;
    
    //数字(可以是二进制、八进制、十六进制)
    let decLiteral: number = 6;
    let hexLiteral: number = 0xf00d;
    let binaryLiteral: number = 0b1010;
    let octalLiteral: number = 0o744;
    
    //字符串
    let name: string = "bob";
    name = "smith";
    
    //使用模版字符串
    let name: string = `Gene`;
    let age: number = 37;
    let sentence: string = `Hello, my name is ${name}.
    I'll be ${age + 1} years old next month.`;
    
    //数组
    let list: number[] = [1, 2, 3];
    //Array<元素类型>
    let list: Array<number> = [1, 2, 3];
    
    //元组 Tuple
    // Declare a tuple type
    let x: [string, number];
    // Initialize it
    x = ["hello", 10]; // OK
    // Initialize it incorrectly
    x = [10, "hello"]; // Error
    
    //枚举
    enum Color {
        Red,
        Green,
        Blue
    }
    let c: Color = Color.Green;
    
    enum Color {
        Red = 1,
        Green,
        Blue
    }
    let c: Color = Color.Green;
    
    enum Color {
        Red = 1,
        Green = 2,
        Blue = 4
    }
    let c: Color = Color.Green;
    
    enum Color {
        Red = 1,
        Green,
        Blue
    }
    let colorName: string = Color[2];
    alert(colorName); // 显示'Green'因为上面代码里它的值是2
    
    //Any
    let notSure: any = 4;
    notSure = "maybe a string instead";
    notSure = false; // okay, definitely a boolean
    
    //Any数组
    let list: any[] = [1, true, "free"];
    list[1] = 100;
    
    //Void
    function warnUser(): void {
        alert("This is my warning message");
    }
    let unusable: void = undefined;
    
    //Null 和 Undefined
    let u: undefined = undefined;
    let n: null = null;
    
    //Never
    // 返回never的函数必须存在无法达到的终点
    function error(message: string): never {
        throw new Error(message);
    }
    // 推断的返回值类型为never
    function fail() {
        return error("Something failed");
    }
    // 返回never的函数必须存在无法达到的终点
    function infiniteLoop(): never {
        while (true) {}
    }
    
    //类型断言
    let someValue1: any = "this is a string";
    let strLength1: number = (someValue1 as string).length;
    
    let someValue: any = "this is a string";
    let strLength: number = (<string>someValue).length;
    
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  • 原文地址:https://www.cnblogs.com/zfc2201/p/8157587.html
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