How do you call a method inherited from another class?

Question

This code cannot run on the last line. I am not sure why.

var Vehicle = function() {
 var age = 21;   //private variable
 this.setAge = function(age2) {age = age2;};
 this.getAge = function() {return age;};
};

var Plane = function() {};
Plane.prototype = Object.create(Vehicle.prototype);

var plane = new Plane();
console.log( plane instanceof Vehicle );
//console.log( plane.getAge() ); //TypeError: plane.getAge is not a function

score 6 · Accepted Answer · answered Dec 15 '15 at 20:29

Your new plane has an empty function for its constructor and the Vehicle constructor has never been called on it. You should call the Vehicle constructor from the plane constructor, by changing:

var Plane = function() {};

to:

var Plane = function ( ) {
    Vehicle.call( this );
};

score 1 · Answer 2 · answered Dec 15 '15 at 20:31

Extending the object could be done with the below

var Vehicle = function() {
    var age = 21;           //private variable
    this.setAge = function(age2) {age = age2;};
    this.getAge = function() {return age;};
};

var Plane = function(){
    Vehicle.apply(this, arguments);
};
Plane.prototype = Object.create(Vehicle.prototype);

var plane = new Plane();
console.log( plane instanceof Vehicle , plane.getAge());

jsFiddle

How do you call a method inherited from another class?

2 Answers2