Javascript从父类(super class)调用方法

Question

我尝试在学生对象的 hello 函数中调用 doSomething 方法，而无需附加原型(prototype)。 Student 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()父级，以便Student拥有Person所做的一切，然后执行this .doSomething():

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

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

然后您可以从学生实例调用 hello():

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

Example Fiddle