TypeScript 接口

TypeScript 接口接口是一系列抽象方法的声明，是一些方法特征的集合，这些方法都应该是抽象的，需要由具体的类去实现，然后第三方就可以通过这组抽象方法调用，让具体的类执行具体的方法。TypeScript 接口定义如下：interface interface_name { }实例以下实例中，我们定义了一个接口 IPerson，接着定义了一个变量 customer，它的类型是 IPerson。customer 实现了接口 IPerson 的属性和方法。TypeScriptinterface IPerson {firstName:string,lastName:string,sayHi: ()=>string}var customer:IPerson = {firstName:"Tom",lastName:"Hanks",sayHi: ():string =>{return "Hi there"}}console.log("Customer 对象 ")console.log(customer.firstName)console.log(customer.lastName)console.log(customer.sayHi())var employee:IPerson = {firstName:"Jim",lastName:"Blakes",sayHi: ():string =>{return "Hello!!!"}}console.log("Employee 对象 ")console.log(employee.firstName)console.log(employee.lastName)需要注意接口不能转换为 JavaScript。 它只是 TypeScript 的一部分。编译以上代码，得到以下 JavaScript 代码：JavaScriptvar customer = {firstName: "Tom",lastName: "Hanks",sayHi: function () { return "Hi there"; }};console.log("Customer 对象 ");console.log(customer.firstName);console.log(customer.lastName);console.log(customer.sayHi());var employee = {firstName: "Jim",lastName: "Blakes",sayHi: function () { return "Hello!!!"; }};console.log("Employee 对象 ");console.log(employee.firstName);console.log(employee.lastName);输出结果为：Customer 对象TomHanksHi thereEmployee 对象JimBlakes联合类型和接口以下实例演示了如何在接口中使用联合类型：TypeScriptinterface RunOptions {program:string;commandline:string[]|string|(()=>string);}// commandline 是字符串var options:RunOptions = {program:"test1",commandline:"Hello"};console.log(options.commandline)// commandline 是字符串数组options = {program:"test1",commandline:["Hello","World"]};console.log(options.commandline[0]);console.log(options.commandline[1]);// commandline 是一个函数表达式options = {program:"test1",commandline:()=>{return "**Hello World**";}};var fn:any = options.commandline;console.log(fn());编译以上代码，得到以下 JavaScript 代码：JavaScript// commandline 是字符串var options = { program: "test1", commandline: "Hello" };console.log(options.commandline);// commandline 是字符串数组options = { program: "test1", commandline: ["Hello", "World"] };console.log(options.commandline[0]);console.log(options.commandline[1]);// commandline 是一个函数表达式options = { program: "test1", commandline: function () { return "**Hello World**"; } };var fn = options.commandline;console.log(fn());输出结果为：HelloHelloWorld**Hello World**接口和数组接口中我们可以将数组的索引值和元素设置为不同类型，索引值可以是数字或字符串。TypeScriptinterface namelist {[index:number]:string}var list2:namelist = ["John",1,"Bran"] / 错误元素 1 不是 string 类型interface ages {[index:string]:number}var agelist:ages;agelist["John"] = 15 // 正确 agelist[2] = "nine" // 错误接口继承接口继承就是说接口可以通过其他接口来扩展自己。Typescript 允许接口继承多个接口。继承使用关键字 extends。单接口继承语法格式：Child_interface_name extends super_interface_name多接口继承语法格式：Child_interface_name extends super_interface1_name, super_interface2_name,…,super_interfaceN_name继承的各个接口使用逗号 , 分隔。单继承实例TypeScriptinterface Person {age:number}interface Musician extends Person {instrument:string}var drummer = <Musician>{};drummer.age = 27drummer.instrument = "Drums"console.log("年龄: "+drummer.age)console.log("喜欢的乐器: "+drummer.instrument)编译以上代码，得到以下 JavaScript 代码：JavaScriptvar drummer = {};drummer.age = 27;drummer.instrument = "Drums";console.log("年龄: " + drummer.age);console.log("喜欢的乐器: " + drummer.instrument);输出结果为：年龄: 27喜欢的乐器: Drums多继承实例TypeScriptinterface IParent1 {v1:number}interface IParent2 {v2:number}interface Child extends IParent1, IParent2 { }var Iobj:Child = { v1:12, v2:23}console.log("value 1: "+Iobj.v1+" value 2: "+Iobj.v2)编译以上代码，得到以下 JavaScript 代码：JavaScriptvar Iobj = { v1: 12, v2: 23 };console.log("value 1: " + Iobj.v1 + " value 2: " + Iobj.v2);输出结果为：value 1: 12 value 2: 23