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Javascript class extension

CONTEXT
I have one Base class called Entity and User and Group are both derived from this object; If I instantiate a user with the ID of 12 for example, the next time I try to do that it returns the same object. I store these in a prototype items variable. To keep these item variables separate I have to declare the User And Group functions separately although they contain the same code.
CODE
Application.prototype.Entity = function() {
};
Application.prototype.Entity.prototype.print = function() {
var container = $("<div class='user-tag'></div>");
container.append("<a class='friend_list ellipsis_overflow' style='background-image:url(\"" + this.entity.pic.icon + "\");'"
+ "href ='user?id=" + this.entity.id + "'>" + this.entity.name + "</a>");
return container;
};
//HOW TO GET RID OF THIS "REPETITION"
Application.prototype.User = function(entity) {
this.entity = entity;
this.entity.pic = this.entity.pic || Application.prototype.default.pic;
if (this.items[this.entity.id]) {
return this.items[this.entity.id];
} else {
this.items[this.entity.id] = this;
}
};
Application.prototype.Group = function(entity) {
this.entity = entity;
this.entity.pic = this.entity.pic || Application.prototype.default.pic;
if (this.items[this.entity.id]) {
return this.items[this.entity.id];
} else {
this.items[this.entity.id] = this;
}
};
// END REPEAT
Application.prototype.Group.prototype = new Application.prototype.Entity();
Application.prototype.User.prototype = new Application.prototype.Entity();
//Application.prototype.User.prototype.constructor = Application.prototype.Entity;
//Application.prototype.Group.prototype.constructor = Application.prototype.Entity; - these don't seem to work
//THESE items VARIABLES HAVE TO REMAIN SEPARATE
Application.prototype.Group.prototype.items = {};
Application.prototype.User.prototype.items = {};
QUESTION
I specifically would like to rid my code of the repetition mentioned above, but if you see any other unnecessary code, please comment. Thanks!

Something like this?
function userAndGroupConstructor(entity) {
this.entity = entity;
this.entity.pic = this.entity.pic || Application.prototype.default.pic;
if (this.items[this.entity.id]) {
return this.items[this.entity.id];
} else {
this.items[this.entity.id] = this;
}
}
Application.prototype.User = function() {
return userAndGroupConstructor.apply(this, arguments)
}
Application.prototype.Group = function() {
return userAndGroupConstructor.apply(this, arguments)
}
You get distinct constructors with distinct prototypes, but avoid duplication.

You can do this:
Application.prototype.Group = Application.prototype.User;
Since Application.prototype.User contains the function reference, you can just assign it to Application.prototype.Group.

Javascript Object-Oriented-Programming

I found a Module pattern in JS:
<script>
var MODULENAME = (function(my, $) {
my.publicVar = "5";
my.publicFn = function() {};
return my;
}(MODULENAME || {}, jQuery));
</script>
However I cannot perform instantiation. Does the module pattern allow for that?

Instantiantion means basically that you'll run a function using new.
So maybe you're looking for this?
var Some = function (param) {
var somePrivateVar = 'private';
this.somePublicVar = 'public';
this.method = function () {
return param;
};
};
var some = new Some('abla');
console.log(some.method());
// some.somePrivateVar === undefined
// some.somePublicVar === 'public'
In your case MODULENAME is an object (object, not a function) with publicVar and publicFn. It's not meant to be instantiated the same way you wouldn't call new jQuery().

Your module object can contain anything. Perhaps you're looking for including a constructor in it:
var MODULENAME = (function(my, $) {
var privateVar = 10;
my.SomeConstructor = function() {
this.publicVar = 5;
}
my.SomeConstructor.prototype.someMethod = function() {};
my.SomeConstructor.prototype.getPrivate = function() { return 10; };
return my;
}(MODULENAME || {}, jQuery));
var instance = new MODULENAME.SomeConstructor();
instance.publicVar; // 5
instance.privateVar; // undefined
instance.getPrivate(); // 10

You can do this also with prototype Inheritance :
var MyClass = function(name)
{
//sharing name within the whole class
this.name = name;
}
MyClass.prototype.getName = function(){
return this.name;//now name is visible to getName method too
}
MyClass.StaticMethod = function()
{
console.log("Im Static");
// and since is not in prototype chain, this.name is not visible
}
var myclass = new MyClass("Carlos");
console.log(myclass.getName())//print "Carlos"
MyClass.StaticMethod()// print "Im Static"
myclass.StaticMethod() // error
Se all this article

Javascript has StackOverflow in IE but not Chrome/Firefox

I've got a class that is basically a native Javascript Array, but it raises events when items are added or removed.
hb.extend( {
Classes: {
Collection: hbClass.inherit({
init: function (arr) {
// get the functions we want to retain
var _on = this.on,
_trigger = this.trigger,
_push = this.push,
_remove = this.remove,
_reset = this.reset,
_from = this.fromArray,
_watch = this.watch;
// Set the object up as an Array
this.__proto__ = Array.prototype;
// get the Array functions we want to use
this.arrPush = this.push;
// reapply the old functions
this.push = _push;
this.remove = _remove;
this.reset = _reset;
this.fromArray = _from;
this.on = _on;
this.trigger = _trigger;
this.watch = _watch;
if (arr && (arr.length && typeof arr !== "string")) this.fromArray(arr, true);
},
fromArray: function (arr, stopEvent) {
this.reset();
for (var i = 0, len = arr.length; i < len; i++) {
this.arrPush(arr[i]);
}
if (!stopEvent) this.trigger('change', this);
},
push: function () {
this.arrPush.apply(this, arguments);
this.trigger('add', this);
this.trigger('change', this);
return this;
},
remove: function (from, to) {
var rest = this.slice((to || from) + 1 || this.length);
this.length = from < 0 ? this.length + from : from;
this.arrPush.apply(this, rest);
this.trigger('remove', this);
this.trigger('change', this);
return this;
},
reset: function () {
this.length = 0;
this.trigger('change', this);
this.trigger('remove', this);
}
})
}
});
There may be better ways to do it, but it works for me.......except in IE.
In IE at the line this.arrPush.appy(this, arguments); under the push method, it hits a Stack Overflow error.
Specifically:
SCRIPT28: Out of stack space
But this does NOT occur in Firefox or Chrome.
Anyone have any advice?
EDIT
Trigger code:
this.hbClass.prototype.trigger = function(type, data, context) {
var listeners, handlers, i, n, handler, scope;
if (!(listeners = this.listeners)) {
return;
}
if (!(handlers = listeners[type])){
return;
}
for (i = 0, n = handlers.length; i < n; i++){
handler = handlers[i];
if (handler.method.call(
handler.context, this, type, data
)===false) {
return false;
}
}
return true;
}

The issue is probably this line:
this.__proto__ = Array.prototype;
as __proto__ is not supported in some versions of IE. It has been codified in the ES6 specification, but that isn't implemented in some versions of IE. I don't understand exactly how your code works, but the safe way to set a prototype is like this:
Working demo: http://jsfiddle.net/jfriend00/ff99G/
function myClass() {
// add new methods to this instance in the constructor
this.fromArray = function() {};
};
// become an array and get all its methods
myClass.prototype = Array.prototype;
var x = new myClass();
Here's an example of the kind of thing you're doing using .prototype that works in IE:
function log(msg) {
var result = document.getElementById("result");
var div = document.createElement("div");
div.innerHTML = msg;
result.appendChild(div);
}
function myClass() {
var _push = this.push;
this.count = function() {
return this.length;
}
this.trigger = function(type, name) {
var str = type;
if (name) {
str += ", " + name;
}
log(str);
}
this.push = function() {
var retVal = _push.apply(this, arguments);
this.trigger("change", "push");
return retVal;
}
};
// become an array and get all its methods
myClass.prototype = Array.prototype;
var x = new myClass();
x.push("foo");
x.push("whatever");
log(x.count());

How can i simply achieve Sencha-Like class inheritance in Backbone?

I'm starting a new Backbone app, and I've been quite fond of the javascript class inheritance system of Sencha Touch 2.0, basically i want to be able to do this :
Helium.define('Application', {
namespace: 'Helium',
constructor: function() {
console.warn('Helium');
}
});
Helium.define('Application', {
namespace: 'MyApp',
extend: 'Backbone.Events',
routers: ['Cards'],
constructor: function() {
console.warn(this);
this.callParent();
console.warn('MyApp');
//console.warn(Helium.getDisplayName(arguments.callee));
}
});
I'm stuck on the prototype chain definition (to make the this.callParent() work) :
var p = Object.create(extend);
var o = _.extend(p, data);
/*function() {
var _o = _.extend(p, data);
_o.constructor.apply(o, arguments);
return _o;
};*/
o.prototype.superclass = p;
o.prototype.callParent = function() {
console.warn(p);
};
Here is the complete micro-implementation so far :
So far, i have done this :
_.mixin({
resolve : function(path, base, separator) {
var parts = path.split('.' || separator),
key = parts.pop();
base = base || window;
while (parts.length) {
part = parts.shift();
base = base[part] = base[part] || {};
}
base[key] = base[key] || {};
return base[key];
}});
Helium = {
define: function(className, data) {
var base = window,
extend = data.extend || {constructor : function() {}},
namespace = data.namespace || null;
if(namespace) {
window[namespace] = window[namespace] || {};
base = window[namespace];
}
if(_.isString(extend)) extend = _.resolve(extend);
if(!extend) throw 'Extend error';
var parts = className.split('.'),
key = parts.pop();
while (parts.length) {
part = parts.shift();
base = base[part] = base[part] || {};
}
delete data.extend;
//delete data.namespace;
data.$name = key;
data.$className = className;
var p = Object.create(extend);
var o = _.extend(p, data);
/*function() {
var _o = _.extend(p, data);
_o.constructor.apply(o, arguments);
return _o;
};*/
o.prototype.superclass = p;
o.prototype.callParent = function() {
console.warn(p);
};
},
getDisplayName: function(callee) {
console.warn('getDisplayName', [this, arguments]);
console.warn(callee.toString());
}
};

I see what you're going for here but if your end game is really being able to call the parent constructor I think it's a little convoluted to try and impose Sencha's inheritance model on Backbone because it is so simple and lightweight and ultimately it has its own inheritance implementation.
Since Backbone's extend() only exists on Backbone classes I think this is a good resource. Unless I'm misunderstanding you I think something along the lines of MyApp.__super__.initialize() in Backbone would be roughly equivalent to this.callParent() in Sencha Touch.

Javascript functional inheritance with prototypes

In Douglas Crockford's JavaScript: The Good Parts he recommends that we use functional inheritance. Here's an example:
var mammal = function(spec, my) {
var that = {};
my = my || {};
// Protected
my.clearThroat = function() {
return "Ahem";
};
that.getName = function() {
return spec.name;
};
that.says = function() {
return my.clearThroat() + ' ' + spec.saying || '';
};
return that;
};
var cat = function(spec, my) {
var that = {};
my = my || {};
spec.saying = spec.saying || 'meow';
that = mammal(spec, my);
that.purr = function() {
return my.clearThroat() + " purr";
};
that.getName = function() {
return that.says() + ' ' + spec.name + ' ' + that.says();
};
return that;
};
var kitty = cat({name: "Fluffy"});
The main issue I have with this is that every time I make a mammal or cat the JavaScript interpreter has to re-compile all the functions in it. That is, you don't get to share the code between instances.
My question is: how do I make this code more efficient? For example, if I was making thousands of cat objects, what is the best way to modify this pattern to take advantage of the prototype object?

Well, you just can't do it that way if you plan on making lots of mammal or cat. Instead do it the old fashioned way (prototype) and inherit by property. You can still do the constructors the way you have above but instead of that and my you use the implicit this and some variable representing the base class (in this example, this.mammal).
cat.prototype.purr = function() { return this.mammal.clearThroat() + "purr"; }
I'd use another name than my for base access and store it in this in the cat constructor. In this example I used mammal but this might not be the best if you want to have static access to the global mammal object. Another option is to name the variable base.

Let me introduce you to Classical Inheritance that never uses prototype. This is a bad coding exercise but will teach you the real Classical Inheritance which always compared to prototypal inheritance:
Make a custructor:
function Person(name, age){
this.name = name;
this.age = age;
this.sayHello = function(){return "Hello! this is " + this.name;}
}
Make another cunstructor that inherits from it:
function Student(name, age, grade){
Person.apply(this, [name, age]);
this.grade = grade
}
Very simple! Student calls(applies) Person on itself with name and age arguments takes care of grade arguments by itself.
Now lets make an instance of Student.
var pete = new Student('Pete', 7, 1);
Out pete object will now contain name, age, grade and sayHello properties. It owns all those properties. They are not uplinked to Person through prototype. If we change Person to this:
function Person(name, age){
this.name = name;
this.age = age;
this.sayHello = function(){
return "Hello! this is " + this.name + ". I am " this.age + " years old";
}
}
pete will no recieve the update. If we call pete.sayHello, ti will return Hello! this is pete. It will not get the new update.

if you want privacy and you dont like protyping you may or may-not like this approach:
(note.: it uses jQuery.extend)
var namespace = namespace || {};
// virtual base class
namespace.base = function (sub, undefined) {
var base = { instance: this };
base.hierarchy = [];
base.fn = {
// check to see if base is of a certain class (must be delegated)
is: function (constr) {
return (this.hierarchy[this.hierarchy.length - 1] === constr);
},
// check to see if base extends a certain class (must be delegated)
inherits: function (constr) {
for (var i = 0; i < this.hierarchy.length; i++) {
if (this.hierarchy[i] == constr) return true;
}
return false;
},
// extend a base (must be delegated)
extend: function (sub) {
this.hierarchy.push(sub.instance.constructor);
return $.extend(true, this, sub);
},
// delegate a function to a certain context
delegate: function (context, fn) {
return function () { return fn.apply(context, arguments); }
},
// delegate a collection of functions to a certain context
delegates: function (context, obj) {
var delegates = {};
for (var fn in obj) {
delegates[fn] = base.fn.delegate(context, obj[fn]);
}
return delegates;
}
};
base.public = {
is: base.fn.is,
inherits: base.fn.inherits
};
// extend a sub-base
base.extend = base.fn.delegate(base, base.fn.extend);
return base.extend(sub);
};
namespace.MyClass = function (params) {
var base = { instance: this };
base.vars = {
myVar: "sometext"
}
base.fn = {
init: function () {
base.vars.myVar = params.myVar;
},
alertMyVar: function() {
alert(base.vars.myVar);
}
};
base.public = {
alertMyVar: base.fn.alertMyVar
};
base = namespace.base(base);
base.fn.init();
return base.fn.delegates(base,base.public);
};
newMyClass = new namespace.MyClass({myVar: 'some text to alert'});
newMyClass.alertMyVar();
the only downside is that because of the privacy scope you can only extend the virtual classes and not the instanceable classes.
here is an example of how i extend the namespace.base, to bind/unbind/fire custom events.
// virtual base class for controls
namespace.controls.base = function (sub) {
var base = { instance: this };
base.keys = {
unknown: 0,
backspace: 8,
tab: 9,
enter: 13,
esc: 27,
arrowUp: 38,
arrowDown: 40,
f5: 116
}
base.fn = {
// bind/unbind custom events. (has to be called via delegate)
listeners: {
// bind custom event
bind: function (type, fn) {
if (fn != undefined) {
if (this.listeners[type] == undefined) {
throw (this.type + ': event type \'' + type + '\' is not supported');
}
this.listeners[type].push(fn);
}
return this;
},
// unbind custom event
unbind: function (type) {
if (this.listeners[type] == undefined) {
throw (this.type + ': event type \'' + type + '\' is not supported');
}
this.listeners[type] = [];
return this;
},
// fire a custom event
fire: function (type, e) {
if (this.listeners[type] == undefined) {
throw (this.type + ': event type \'' + type + '\' does not exist');
}
for (var i = 0; i < this.listeners[type].length; i++) {
this.listeners[type][i](e);
}
if(e != undefined) e.stopPropagation();
}
}
};
base.public = {
bind: base.fn.listeners.bind,
unbind: base.fn.listeners.unbind
};
base = new namespace.base(base);
base.fire = base.fn.delegate(base, base.fn.listeners.fire);
return base.extend(sub);
};

To proper use Javascript-prototype based inheritance you could use fastClass https://github.com/dotnetwise/Javascript-FastClass
You have the simpler inheritWith flavor:
var Mammal = function (spec) {
this.spec = spec;
}.define({
clearThroat: function () { return "Ahem" },
getName: function () {
return this.spec.name;
},
says: function () {
return this.clearThroat() + ' ' + spec.saying || '';
}
});
var Cat = Mammal.inheritWith(function (base, baseCtor) {
return {
constructor: function(spec) {
spec = spec || {};
baseCtor.call(this, spec);
},
purr: function() {
return this.clearThroat() + " purr";
},
getName: function() {
return this.says() + ' ' + this.spec.name + this.says();
}
}
});
var kitty = new Cat({ name: "Fluffy" });
kitty.purr(); // Ahem purr
kitty.getName(); // Ahem Fluffy Ahem
And if you are very concerned about performance then you have the fastClass flavor:
var Mammal = function (spec) {
this.spec = spec;
}.define({
clearThroat: function () { return "Ahem" },
getName: function () {
return this.spec.name;
},
says: function () {
return this.clearThroat() + ' ' + spec.saying || '';
}
});
var Cat = Mammal.fastClass(function (base, baseCtor) {
return function() {
this.constructor = function(spec) {
spec = spec || {};
baseCtor.call(this, spec);
};
this.purr = function() {
return this.clearThroat() + " purr";
},
this.getName = function() {
return this.says() + ' ' + this.spec.name + this.says();
}
}
});
var kitty = new Cat({ name: "Fluffy" });
kitty.purr(); // Ahem purr
kitty.getName(); // Ahem Fluffy Ahem
Btw, your initial code doesn't make any sense but I have respected it literally.
fastClass utility:
Function.prototype.fastClass = function (creator) {
var baseClass = this, ctor = (creator || function () { this.constructor = function () { baseClass.apply(this, arguments); } })(this.prototype, this)
var derrivedProrotype = new ctor();
if (!derrivedProrotype.hasOwnProperty("constructor"))
derrivedProrotype.constructor = function () { baseClass.apply(this, arguments); }
derrivedProrotype.constructor.prototype = derrivedProrotype;
return derrivedProrotype.constructor;
};
inheritWith utility:
Function.prototype.inheritWith = function (creator, makeConstructorNotEnumerable) {
var baseCtor = this;
var creatorResult = creator.call(this, this.prototype, this) || {};
var Derrived = creatorResult.constructor ||
function defaultCtor() {
baseCtor.apply(this, arguments);
};
var derrivedPrototype;
function __() { };
__.prototype = this.prototype;
Derrived.prototype = derrivedPrototype = new __;
for (var p in creatorResult)
derrivedPrototype[p] = creatorResult[p];
if (makeConstructorNotEnumerable && canDefineNonEnumerableProperty) //this is not default as it carries over some performance overhead
Object.defineProperty(derrivedPrototype, 'constructor', {
enumerable: false,
value: Derrived
});
return Derrived;
};
define utility:
Function.prototype.define = function (prototype) {
var extendeePrototype = this.prototype;
if (prototype)
for (var p in prototype)
extendeePrototype[p] = prototype[p];
return this;
}
[* Disclaimer, I am the author of the open source package and the names of the methods themselves might be renamed in future` *]