Class Inheritance using Object.extendsObject and this.name

[OliverDoesereck]

I am trying something thats pretty simple and should work fine, as there are more than enough example Script Includes, but something just doesnt work.

Animal Class:

var Animal = Class.create();
Animal.prototype = {
    initialize: function(name) {
        this.name = name;
        this.speed = 0;
    },

    run: function(speed) {
        this.speed += speed;
        gs.log(this.name+" runs with speed "+this.speed+".");
    },

    stop: function() {
        this.speed = 0;
        gs.log(this.name+" stands still.");
    },

    type: 'Animal'
};

Rabbit Class, extending Animal Class:

var Rabbit = Class.create();
Rabbit.prototype = Object.extendsObject(Animal, {

	hide: function() {
		gs.log(this.name + " hides!");
	},
	
	type: "Rabbit"
});

As already learned, Object.extendsObject is a ServiceNow extension of prototype.js  (Script Include: PrototypeServer)

When executing the following:

var rabbit = new Rabbit("White Rabbit");
rabbit.run(5);

The Output is:

*** Script:  runs with speed 5.

Findings:
- this.name is not being set in the constructor. If I exchange "name" with "myName", everything works fine when using this.myName.
- using Object.extend(new Animal(), {}) works fine too. But thats the legacy way.
- using the Class Extender Method from Raymond Ferguson here: https://community.servicenow.com/community?id=community_question&sys_id=fb3f4be1dbdcdbc01dcaf3231f9619b1 works fine too.
- Creating a new Animal Object works fine with "name"

Is "name" protected or reserved when extending classes using Object.extendsClass? The parent constructor is being called just fine. this.speed is being used correctly.

[Sebastian R_]

An instance of a script include always contains a variable "name" (don´t know why). It´s empty and I assume this is somehow protected if you clone/exten a script include.

typeof new Animal().name; // -> string

I think it´s the best to use another name for it.

[Geni]

when calling Object.objectExtends you need to manually call the initialization method of the class your extending in your case modify your rabbit script include to the following:

var Rabbit = Class.create();
Rabbit.prototype = Object.extendsObject(Animal, {

       initialize: function() {
		Animal.prototype.initialize.call(this);
      },

	hide: function() {
		gs.log(this.name + " hides!");
	},
	
	type: "Rabbit"
});

By calling the Animal prototype initialize and feeding the instance of this you will apply your initialize logic to your extended class.

[BillMartin]

Hi @OliverDoesereck ,

I have created this easy to follow example where you can inherit from a class using Object.extendsObject() function. 

You can find more details here: Master Good Software Architecture with Object.extendsObject() | A Guide for ServiceNow Developers