接口的继承与实现 ：

interface A{

    save(o:any):void;

    select();

    update();

    delete();
}



interface B extends A{

    count():number;

    page();

}

class User implements B {
    count(): number {
        throw new Error("Method not implemented.");
    }
    page() {
        throw new Error("Method not implemented.");
    }
    save(o: any): void {
        throw new Error("Method not implemented.");
    }
    select() {
        throw new Error("Method not implemented.");
    }
    update() {
        throw new Error("Method not implemented.");
    }
    delete() {
        throw new Error("Method not implemented.");
    }
    
    constructor(parameters) {
        
    }
}

接口的多实现：

interface A{

    save(o:any):void;

    select();

    update();

    delete();
}

interface B {

    count():number;

    page();

}

class User1 implements B,A {
    count(): number {
        throw new Error("Method not implemented.");
    }
    page() {
        throw new Error("Method not implemented.");
    }
    save(o: any): void {
        throw new Error("Method not implemented.");
    }
    select() {
        throw new Error("Method not implemented.");
    }
    update() {
        throw new Error("Method not implemented.");
    }
    delete() {
        throw new Error("Method not implemented.");
    }
    
    constructor(parameters) {
        
    }
}

接口的多继承：

interface A{

    save(o:any):void;

    select();

    update();

    delete();
}

interface X{
    x();
}

// 接口多继承
interface B extends A,X{

    count():number;

    page();

}

class User2 implements B {
    x() {
        throw new Error("Method not implemented.");
    }
    count(): number {
        throw new Error("Method not implemented.");
    }
    page() {
        throw new Error("Method not implemented.");
    }
    save(o: any): void {
        throw new Error("Method not implemented.");
    }
    select() {
        throw new Error("Method not implemented.");
    }
    update() {
        throw new Error("Method not implemented.");
    }
    delete() {
        throw new Error("Method not implemented.");
    }
    
    constructor(parameters) {
        
    }
}

扩展：

// TS中
class Point2D {
    x:number;
    y:number;
}

// 接口继承类
interface Point3D extends Point2D{
    z:number;
}

let a:Point3D={x:1,y:2,z:3};//创建对象，未调用构造器
let a1:Point2D=new Point2D();//类实例化
// let a3:Point3D=new Point3D();//接口不能实例化