JavaScript, ES6 the class inheritance

Class inheritance

extends  connstructor  super

Example 1:

       Father {class 
            constructor () {} 
            Money () { 
                the console.log ( "10000 block" ); 
            } 
        } 
        // subclass inherits the parent class using the extends Son Father 
        class {} Father Son extends
         var SS = new new Father (); 
        SS .money (); 
        // 10000 block

Example 2:

        class Fa {
            constructor(x, y){
                this.x = x;
                this.y = y;
            }
            sum(){
                var su = this.x + this.y;
                console.log(su);
            }
        }
        class Son extends Fa{
            constructor(x, y){ // constructor用于存放类的共有属性
                this.x = x;
                this.y = y;
            }
        }
        var son = new Son(1, 2);
        son.sum();
        // 输出：Uncaught ReferenceError: Must call super constructor in derived 
        class before accessing 'this' or returning from derived constructor

the reason:

    Parameters (1,2) son instance of an object is in fact points to a subclass of Son constructor (x, y) is not the parent class Fa constructor (x, y) can not use sum () method.

Improve:

   super keyword is used to access and to call on the parent class constructor. You can call the constructor of the parent class, you can also call a normal function of the parent class

        {Fa of the class 
            constructor (X, Y) { 
                in this.x = X; 
                this.y from Y =; 
            } 
            SUM () { 
                var = SU + in this.x this.y from; 
                the console.log (SU); 
            } 
        } 
        class the extends Son {FA 
            constructor (X, Y) { 
                Super (X, Y); // constructor is called the parent class constructor 
            } 
        } 
        var new new Son = Son (. 1, 2); 
        son.sum (); 
        //. 3