非接口约束

function printA(labelObj:{label:string}){console.log(labelObj);
}printA({label:'你好'
})//跳过额外字段的检测
// 第一种断言 ：printA({label:'你好',name:'laney'
} as {label:string})//第二种方式：添加字符串的索引签名function printB(labelObj:{label:string,[propName:string]:any}){console.log(labelObj);
}
printB({label:'你好',name:'laney',age:20
})//第三种：将字面量赋值给另外一个变量var obj = {label:'你好',name:'laney'
};printA(obj)

使用接口

//使用接口 ,一种规范
namespace INK1 {interface labelValue {label: string;apple: string;// [propName:string]:any;   //添加字符串的索引签名// size?:string; //可传可不传};function printB(labelObj: labelValue) {console.log('labelObj.label');console.log(labelObj);}// 第一种断言 ：printB({label: '你好',// size:'10',apple: 'ddd'} as { apple: string; label: string })//第二种方式：添加字符串的索引签名printB({label: '你好',size: 10,age: 10})//第三种：将字面量赋值给另外一个变量var obj = {label: '你好',size: 10,age: 10}}

接口计算（普通计算和数组计算）

//函数类型接口：对函数的参数以及返回值进行约束
namespace FunctionA {//不使用接口var add1 = function(a:number,b:number):number{return a+b;}//使用函数接口interface CalcTwo {(a:number,b:number):number}var add2:CalcTwo = function(a1:number,b1:number):number {return a1+b1;}interface encrypt{(key:string,value:string):string;}var md5:encrypt=function(key:string,value:string):string{//模拟操作return key+value;}console.log(md5('name','tony'))}
namespace MathAdd {interface CalcTwo {(a: number, b: number): number}/*** 计算数组被某种算法运算的结果* @param {number[]} arr  数组* @param {CalcTwo} calc  用户指定的算法函数* @param {number} initVal  传入初始值* @returns {number}  得到最终运算结果**/function calcArr(arr: number[], calc: CalcTwo, initVal: number): number {// var result = initVal;// arr.forEach((value,index)=>{//     result = calc(result,value)  // });// return result// 高阶函数return arr.reduce(function (a, b) {return calc(a, b)}, initVal)}var arr: number[] = [1, 3, 5, 7, 9];var sum = function (a1: number, b1: number): number {return a1 + b1;}var multipy = function (a1: number, b1: number): number {return a1 * b1;}//相加var p1 = calcArr(arr, sum, 10);console.log('相加:' + p1);//相乘var p2 = calcArr(arr, multipy, 10);console.log('相乘:' + p2);}

接口定义，数组和对象取值

namespace ArrG {interface UserArr {[index: number]: string}//1.对数据的约束var arr1: UserArr = ['aaa', '111'];// var  arr2:UserArr = ['aaa',111]; //错误console.log(arr1[0])//2. 对对象的约束interface UserObj {[index: string]: string}var obj1: UserObj = { name: "张三" } //正确// var obj1:UserObj = {name:112} //错误console.log(obj1)
}

类继承接口

// 类类型接口用来规范一个类的内容。
// 类实现接口本质上 即类遵循接口的约束，接口里面写了多少个函数、参数，实现的类里面也要写相同的函数、参数。
namespace TT1 {interface FullName {  username: string;  }  //WebCoder 需要遵循接口FullName的约束class WebCoder implements FullName {fruit:string;username:string;constructor(fruit01:string,username:string) {this.fruit = fruit01;this.username = username;}}var p1 = new WebCoder('苹果','Alice');console.log(p1);}namespace TT2 {// 可以在接口中描述一个方法，并在类里具体实现它的功能，// 如同下面的setName方法一样interface FullName {  username: string;  setName(name:string):void;getName():void} class Person implements FullName {username:string;constructor(username:string) {this.username = username;}setName(str:string){this.username = str;}getName(){console.log(this.username);}}var p1 = new Person('laney');p1.setName('blood');p1.getName();
}

多接口继承

// 6.2 接口可以继承接口namespace PE1 {interface Animal {eat(): void;}interface Female {usernmae: string;}interface Male {age: string}//接口 Person 继承了接口Animal//单继承。只继承了一个接口interface Person extends Animal {work(): void;}//多接口继承// 接口名 extends 接口1,接口2,....接口n//继承多个接口用逗号分开interface Cat extends Animal, Female, Male {color: string;}class webFront implements Person {name: string;constructor(name: string) {this.name = name;}eat() {console.log(this.name + '吃西瓜')}work() {console.log(this.name + '写代码')}}var w1 = new webFront('张三');w1.eat();//类继承类并实现接口：  WebFront继承类Programmer 并实现接口Person}//类可以实现类， 也可以实现接口namespace PE2 {interface Animal {eat(): void;}interface Person extends Animal {work(): void;}class Programer {name: string;constructor(name: string) {this.name = name;}codeing(code: string) {console.log(this.name + code);}}class webFront extends Programer implements Person {constructor(name: string) {super(name)}eat() {console.log(this.name + '吃苹果')}work() {console.log(this.name + '写代码')}}var w2 = new webFront('Tony');w2.eat();
}//接口继承类
namespace PE3 {class Point {x: number;y: number;constructor(x: number, y: number) {this.x = x;this.y = y;}shape() {console.log('原型');}}interface Point3D extends Point {z: number;eat(): void;}var ts: Point3D = {x: 1,y: 2,z: 3,shape() {console.log('kkkk');},eat() {console.log('喜欢吃水果');}}console.log(ts);
}

备注：强制转换的使用

function getLength(x: number | string): number {return x.toString().length;//  return x.length; //错误
}// 方式一： <类型> 值 
function getLength1(x: number | string): number {if ((<string>x).length) {return (<string>x).length} else {return x.toString().length}
}// 方式二： 值 as 类型function getLength2(x: number | string): number {if ((x as string)) {return (x as string).length} else {return x.toString().length;}
}