TypeScript入门-语法篇

转自 –> TypeScript入门-语法篇

自学笔记, 基于官方教程上的代码, 添加注释.

官方教程:

Handbook

---

基本类型 Basic Types

// 1. Boolean,布尔
var isDone: boolean = false;

console.log(isDone);

// 2. Number,数值
var height: number = 6;

console.log(height);

// 3. String,字符串
var name: string = "bob"; // 可以双引号
var name1: string = 'tom'; // 也可以单引号

console.log(name);
console.log(name1);

// 4. Array,数组
var list:number[] = [1, 2, 3]; // 写法1
var list1:Array = [1, 2, 3]; // 写法2

console.log(list);
console.log(list1);

// 5. Enum,枚举
enum Color {Red, Green, Blue}
var c: Color = Color.Green;

console.log(c); // 获取值
console.log(Color[c]); // 获取键, string
console.log(Color["Green"]); // 获取值

// # enum的值默认从0开始递增, 也可以自己指定
enum Color1 {Red = 1, Green = 2, Blue = 4}
var c1: Color1 = Color1.Green;

console.log(c1); // 获取值

// 6. Any,任意对象
// # 需要小心使用, 会改变数据类型
var anylist:any[] = [1, true, "free"];

anylist[2] = 100;

console.log(anylist);

// 7. Void,方法不返回值

function warnUser(): void {
    console.log("This is my warning message");
}

warnUser();

接口 Interfaces

第一个接口 Our First Interface

interface LabelledValue {
    label: string;
}

function printLabel(labelledObj: LabelledValue) {
    console.log(labelledObj.label);
}

var myObj = {label: "only label"};
var myObj1 = {size: 10, label: "Size 10 Object"};

// # 接口是鸭子类型, 只要是有label的对象都可以传进去
printLabel(myObj);
printLabel(myObj1);

可选属性 Optional Properties

interface SquareConfig {
    color?: string; // 用?来表示可选属性
    width?: number;
}

function createSquare(config: SquareConfig): {color: string; area: number} {
    var newSquare = {color: "white", area: 100}; // 默认值
    if (config.color) {
        newSquare.color = config.color;
    }
    if (config.width) {
        newSquare.area = config.width * config.width;
    }
    return newSquare;
}

var mySquare = createSquare({color: "black"});
var mySquare1 = createSquare({width: 20});

console.log(mySquare);
console.log(mySquare1);

函数类型 Function Types

interface SearchFunc {
    (source: string, subString: string): boolean; // 表示一个接受2个string参数, 返回bool的函数
}

var mySearch: SearchFunc;
mySearch = function(source: string, subString: string): boolean {
    var result = source.search(subString);
    if (result == -1) {
        return false;
    }
    else {
        return true;
    }
};

var result: boolean = mySearch("test", "te");

console.log(result);

数组类型 Array Types

interface StringArray {
    [index: number]: string; // 表示string数组
}

var myArray: StringArray;
myArray = ["Bob", "Fred"];

console.log(myArray["0"]);
console.log(myArray["1"]);

类类型 Class Types

interface ClockStatic {
    new (hour: number, minute: number);
}

// # 这里会报错. 因为只有实例部分才检查, 而构造函数是静态部分
//class Clock implements ClockStatic  {
//    currentTime: Date;
//    constructor(h: number, m: number) { }
//}

class Clock {
    currentTime: Date;
    constructor(h: number, m: number) { }
}

// # 这里需要注意
// # 我们直接使用class,这样就会检查签名
var cs: ClockStatic = Clock;
var newClock: ClockStatic = new cs(7, 30);

console.log(newClock);

继承接口 Extending Interfaces

interface Shape {
    color: string;
}

interface PenStroke {
    penWidth: number;
}

interface Square extends Shape, PenStroke { // 使用extends继承接口
    sideLength: number;
}

var square = {};
square.color = "blue";
square.sideLength = 10;
square.penWidth = 5.0;

混合类型 Hybrid Types

interface Counter {
    (start: number): string;
    interval: number;
    reset(): void;
}

var c: Counter;
c(10); // c可以当函数
c.reset(); // c也可以当对象
c.interval = 5.0; // c的属性

类 Classes

类 Classes

class Greeter {
    greeting: string; // 属性
    constructor(message: string) { // 构造函数
        this.greeting = message;
    }
    greet(): string { // 方法
        return "Hello, " + this.greeting;
    }
}

var greeter = new Greeter("world");
var result = greeter.greet();

console.log(result);

继承 Inheritance

class Animal {
    name:string;
    constructor(theName: string) { this.name = theName; }
    move(meters: number = 0) {
        console.log(this.name + " moved " + meters + "m.");
    }
}

class Snake extends Animal { // 使用extends关键字来继承
    constructor(name: string) { super(name); }
    move(meters = 5) {
        console.log("Slithering...");
        super.move(meters);
    }
}

class Horse extends Animal {
    constructor(name: string) { super(name); }
    move(meters = 45) {
        console.log("Galloping...");
        super.move(meters);
    }
}

var sam = new Snake("Sammy the Python");
var tom: Animal = new Horse("Tommy the Palomino");

sam.move();
tom.move(34);

公/私 修饰器 Private/Public modifiers

默认公有 Public by default

class Animal {
    private name:string; // 除非指定为private, 否则默认是public
    constructor(theName: string) { this.name = theName; }
    move(meters: number) {
        alert(this.name + " moved " + meters + "m.");
    }
}

理解私有 Understanding private

class Animal {
    private name:string;
    constructor(theName: string) { this.name = theName; }
}

class Rhino extends Animal {
    constructor() { super("Rhino"); }
}

class Employee {
    private name:string;
    constructor(theName: string) { this.name = theName; }
}

var animal = new Animal("Goat");
var rhino = new Rhino();
var employee = new Employee("Bob");

animal = rhino;
//animal = employee; // # 这里会报错. 虽然Animal和Employee属性名一致, 但是私有属性来源不一致

class A {
    public name: string;
    echo() {}
}

class B {
    public name: string;
    echo() {}
}

var a = new A();
var b = new B();

a = b; // 公有属性则没有关系

参数属性 Parameter properties

class Animal {
    constructor(private name: string) { } // 可以在构造方法用private直接指定属性,省去一步
    move(meters: number) {
        console.log(this.name + " moved " + meters + "m.");
    }
}

var dog = new Animal("dog");

dog.move(3);

访问器 Accessors

var passcode = "secret passcode";

class Employee {
    private _fullName: string;

    get fullName(): string { // 读属性. # 需要编译版本为ECMAScript 5
        return this._fullName;
    }

    set fullName(newName: string) { // 写属性. # 需要编译版本为ECMAScript 5
        if (passcode && passcode == "secret passcode") {
            this._fullName = newName;
        }
        else {
            console.log("Error: Unauthorized update of employee!");
        }
    }
}

var employee = new Employee();
employee.fullName = "Bob Smith";
if (employee.fullName) {
    console.log(employee.fullName);
}

静态属性 Static Properties

class Grid {
    static origin = {x: 0, y: 0}; // 用static定义静态属性
    calculateDistanceFromOrigin(point: {x: number; y: number;}) {
        var xDist = (point.x - Grid.origin.x);
        var yDist = (point.y - Grid.origin.y);
        return Math.sqrt(xDist * xDist + yDist * yDist) / this.scale;
    }
    constructor (public scale: number) { }
}

var grid1 = new Grid(1.0);  // 1x scale
var grid2 = new Grid(5.0);  // 5x scale

console.log(grid1.calculateDistanceFromOrigin({x: 10, y: 10}));
console.log(grid2.calculateDistanceFromOrigin({x: 10, y: 10}));

Advanced Techniques

模块 Modules

函数 Functions

泛型 Generics

异常 Common Errors

Mixins

Declaration Merging

Type Inference

Type Compatibility

Writing .d.ts files