来自父类(super class)的 Javascript 调用方法

Question

我尝试在没有原型(prototype)的学生对象的 hello 函数中调用方法 doSomething 只是附加到这个上。学生扩展了 Person 对象。

function Person(name){
    this._name = name;
    this.doSomething = function () {
        console.log('doSomething');
     }
}

function Student (name, grade) {
    this._name = name;
    this._grade = grade;

    this.hello = function  () {
        //How i can call doSomething() here
    }
}

Answer 1

您需要在构造函数中.call() parent 以便Student 拥有Person 所做的一切，然后执行这个.doSomething():

function Student (name, grade) {
    Person.call(this, name); // extends
    this._grade = grade;

    this.hello = function  () {
        this.doSomething();
    };
}

然后你可以从一个学生实例调用hello():

var student = new Student("t","A")
student.hello(); // logs 'doSomething'

Example Fiddle