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javascript class in hta [duplicate]

how to create a class in classic jscript? (not jscript.net)
And, how to reference this class?.
I tried with
class someclass {
}
but it does not work.

There are no classes in jscript. You can make an object constructor:
function someclass() {
this.answer = 42;
}
You use it like a class:
var obj = new someclass();
To make methods you add functions to its prototype:
someclass.prototype.getAnswer = function() {
return this.answer;
}
Usage:
var ans = obj.getAnswer();

There are not classes as such, but here's a simple example of how to get basic object-oriented functionality. If this is all you need, great, but if you're after other features of classes, such as inheritance, someone more knowledgeable than myself will have to help.
function SomeClass(n) {
this.some_property = n;
this.some_method = function() {
WScript.Echo(this.some_property);
};
}
var foo = new SomeClass(3);
var bar = new SomeClass(4);
foo.some_method();
bar.some_property += 2;
bar.some_method();

Most recent:
JavaScript/Reference/Classes
Answer from 2011:
You don't really have classes on Javascript, but you have something similar. Check this example on jsFiddle
var classA = function() { // declaring a "class"
this.something = "Text"; // a public class field
};
classA.prototype.b = " b "; // a class field
classA.c = "c"; // a static field
classA.prototype.d = function(x) { // a public class method
};
classA.e = function(x){ // a public static method
};
var a = new classA(); // instantiate a class
Read more on MDC...

Define a function with the name of the class. Any var defined within it as this.whatever will act as a class member:
function SomeClass() {
this.a;
this.b;
}
Then add methods to the prototype:
SomeClass.prototype.methodA = function() {
this.a++;
}
SomeClass.prototype.methodB = function() {
this.b++;
}
I believe you can also define methods inside the constructor like this, but I've not used this syntax for a long time.
function SomeClass {
this.a = 0;
// Method definition
this.methodA = function() {
this.a++;
}
}

Bear with me as I only faintly grasp this myself:
Javascript does not have classes. It has objects. To replicate a class, you create an object. To create "instances" of that "class", you duplicate that object. There are a few ways to do this. One is to create a function that returns an object, then call the function, like so:
function Car(brand, year) {
return {
brand: brand,
year: year
}
}
var modelT = Car("Ford", 1900); //or whenever the model T came out
modelT.brand == "Ford" //true
modelT.year == 1900; //true
Another way is to create an object that is a function and create a "new" of that object. The catch is you have to use new, and that's rather misleading.
var Car = function(make, year) {
this.make = make;
this.year = year;
};
var x = new Car("ford", 1990);
//same tests hold true from earlier example
In my opinion the best way is to use Object.create because it best represents what's actually happening:
var Car = (function() {
var self = Object.create({}, {
make: {
value: "Ford"
}
year: {
value: 1900
}
});
return self;
})();
var modelT = Object.create(Car, {
make: {
value: "Model T"
},
year: {
value: 1901
}
});
Unfortunately, this is extremely cumbersome.
Edit:
This is an extremely helpful resource: JavaScript "classes"

Classes in Jscript (.Net?): http://www.functionx.com/jscript/Lesson05.htm
And Powershell supports it (as well as VisualBasic, even F#). Now I see the question says not in .net. But in my defense, I was googling jscript classes, and this is where I landed.
Add-Type #'
class FRectangle {
var Length : double;
var Height : double;
function Perimeter() : double {
return (Length + Height) * 2; }
function Area() : double {
return Length * Height; } }
'# -Language JScript
[frectangle]::new()
Length Height
------ ------
0 0

Class vs alternate ways of accomplishing it [duplicate]

I prefer to use OOP in large scale projects like the one I'm working on right now. I need to create several classes in JavaScript but, if I'm not mistaken, there are at least a couple of ways to go about doing that. What would be the syntax and why would it be done in that way?
I would like to avoid using third-party libraries - at least at first.
Looking for other answers, I found the article Object-Oriented Programming with JavaScript, Part I: Inheritance - Doc JavaScript that discusses object-oriented programming in JavaScript. Is there a better way to do inheritance?

Here's the way to do it without using any external libraries:
// Define a class like this
function Person(name, gender){
// Add object properties like this
this.name = name;
this.gender = gender;
}
// Add methods like this. All Person objects will be able to invoke this
Person.prototype.speak = function(){
alert("Howdy, my name is" + this.name);
};
// Instantiate new objects with 'new'
var person = new Person("Bob", "M");
// Invoke methods like this
person.speak(); // alerts "Howdy, my name is Bob"
Now the real answer is a whole lot more complex than that. For instance, there is no such thing as classes in JavaScript. JavaScript uses a prototype-based inheritance scheme.
In addition, there are numerous popular JavaScript libraries that have their own style of approximating class-like functionality in JavaScript. You'll want to check out at least Prototype and jQuery.
Deciding which of these is the "best" is a great way to start a holy war on Stack Overflow. If you're embarking on a larger JavaScript-heavy project, it's definitely worth learning a popular library and doing it their way. I'm a Prototype guy, but Stack Overflow seems to lean towards jQuery.
As far as there being only "one way to do it", without any dependencies on external libraries, the way I wrote is pretty much it.

The best way to define a class in JavaScript is to not define a class.
Seriously.
There are several different flavors of object-orientation, some of them are:
class-based OO (first introduced by Smalltalk)
prototype-based OO (first introduced by Self)
multimethod-based OO (first introduced by CommonLoops, I think)
predicate-based OO (no idea)
And probably others I don't know about.
JavaScript implements prototype-based OO. In prototype-based OO, new objects are created by copying other objects (instead of being instantiated from a class template) and methods live directly in objects instead of in classes. Inheritance is done via delegation: if an object doesn't have a method or property, it is looked up on its prototype(s) (i.e. the object it was cloned from), then the prototype's prototypes and so on.
In other words: there are no classes.
JavaScript actually has a nice tweak of that model: constructors. Not only can you create objects by copying existing ones, you can also construct them "out of thin air", so to speak. If you call a function with the new keyword, that function becomes a constructor and the this keyword will not point to the current object but instead to a newly created "empty" one. So, you can configure an object any way you like. In that way, JavaScript constructors can take on one of the roles of classes in traditional class-based OO: serving as a template or blueprint for new objects.
Now, JavaScript is a very powerful language, so it is quite easy to implement a class-based OO system within JavaScript if you want to. However, you should only do this if you really have a need for it and not just because that's the way Java does it.

ES2015 Classes
In the ES2015 specification, you can use the class syntax which is just sugar over the prototype system.
class Person {
constructor(name) {
this.name = name;
}
toString() {
return `My name is ${ this.name }.`;
}
}
class Employee extends Person {
constructor(name, hours) {
super(name);
this.hours = hours;
}
toString() {
return `${ super.toString() } I work ${ this.hours } hours.`;
}
}
Benefits
The main benefit is that static analysis tools find it easier to target this syntax. It is also easier for others coming from class-based languages to use the language as a polyglot.
Caveats
Be wary of its current limitations. To achieve private properties, one must resort to using Symbols or WeakMaps. In future releases, classes will most likely be expanded to include these missing features.
Support
Browser support isn't very good at the moment (supported by nearly everyone except IE), but you can use these features now with a transpiler like Babel.
Resources
Classes in ECMAScript 6 (final semantics)
What? Wait. Really? Oh no! (a post about ES6 classes and privacy)
Compatibility Table – Classes
Babel – Classes

I prefer to use Daniel X. Moore's {SUPER: SYSTEM}. This is a discipline that provides benefits such as true instance variables, trait based inheritance, class hierarchies and configuration options. The example below illustrates the use of true instance variables, which I believe is the biggest advantage. If you don't need instance variables and are happy with only public or private variables then there are probably simpler systems.
function Person(I) {
I = I || {};
Object.reverseMerge(I, {
name: "McLovin",
age: 25,
homeState: "Hawaii"
});
return {
introduce: function() {
return "Hi I'm " + I.name + " and I'm " + I.age;
}
};
}
var fogel = Person({
age: "old enough"
});
fogel.introduce(); // "Hi I'm McLovin and I'm old enough"
Wow, that's not really very useful on it's own, but take a look at adding a subclass:
function Ninja(I) {
I = I || {};
Object.reverseMerge(I, {
belt: "black"
});
// Ninja is a subclass of person
return Object.extend(Person(I), {
greetChallenger: function() {
return "In all my " + I.age + " years as a ninja, I've never met a challenger as worthy as you...";
}
});
}
var resig = Ninja({name: "John Resig"});
resig.introduce(); // "Hi I'm John Resig and I'm 25"
Another advantage is the ability to have modules and trait based inheritance.
// The Bindable module
function Bindable() {
var eventCallbacks = {};
return {
bind: function(event, callback) {
eventCallbacks[event] = eventCallbacks[event] || [];
eventCallbacks[event].push(callback);
},
trigger: function(event) {
var callbacks = eventCallbacks[event];
if(callbacks && callbacks.length) {
var self = this;
callbacks.forEach(function(callback) {
callback(self);
});
}
},
};
}
An example of having the person class include the bindable module.
function Person(I) {
I = I || {};
Object.reverseMerge(I, {
name: "McLovin",
age: 25,
homeState: "Hawaii"
});
var self = {
introduce: function() {
return "Hi I'm " + I.name + " and I'm " + I.age;
}
};
// Including the Bindable module
Object.extend(self, Bindable());
return self;
}
var person = Person();
person.bind("eat", function() {
alert(person.introduce() + " and I'm eating!");
});
person.trigger("eat"); // Blasts the alert!
Disclosure: I am Daniel X. Moore and this is my {SUPER: SYSTEM}. It is the best way to define a class in JavaScript.

var Animal = function(options) {
var name = options.name;
var animal = {};
animal.getName = function() {
return name;
};
var somePrivateMethod = function() {
};
return animal;
};
// usage
var cat = Animal({name: 'tiger'});

Following are the ways to create objects in javascript, which I've used so far
Example 1:
obj = new Object();
obj.name = 'test';
obj.sayHello = function() {
console.log('Hello '+ this.name);
}
Example 2:
obj = {};
obj.name = 'test';
obj.sayHello = function() {
console.log('Hello '+ this.name);
}
obj.sayHello();
Example 3:
var obj = function(nameParam) {
this.name = nameParam;
}
obj.prototype.sayHello = function() {
console.log('Hello '+ this.name);
}
Example 4: Actual benefits of Object.create(). please refer [this link]
var Obj = {
init: function(nameParam) {
this.name = nameParam;
},
sayHello: function() {
console.log('Hello '+ this.name);
}
};
var usrObj = Object.create(Obj); // <== one level of inheritance
usrObj.init('Bob');
usrObj.sayHello();
Example 5 (customised Crockford's Object.create):
Object.build = function(o) {
var initArgs = Array.prototype.slice.call(arguments,1)
function F() {
if((typeof o.init === 'function') && initArgs.length) {
o.init.apply(this,initArgs)
}
}
F.prototype = o
return new F()
}
MY_GLOBAL = {i: 1, nextId: function(){return this.i++}} // For example
var userB = {
init: function(nameParam) {
this.id = MY_GLOBAL.nextId();
this.name = nameParam;
},
sayHello: function() {
console.log('Hello '+ this.name);
}
};
var bob = Object.build(userB, 'Bob'); // Different from your code
bob.sayHello();
To keep answer updated with ES6/ ES2015
A class is defined like this:
class Person {
constructor(strName, numAge) {
this.name = strName;
this.age = numAge;
}
toString() {
return '((Class::Person) named ' + this.name + ' & of age ' + this.age + ')';
}
}
let objPerson = new Person("Bob",33);
console.log(objPerson.toString());

I think you should read Douglas Crockford's Prototypal Inheritance in JavaScript and Classical Inheritance in JavaScript.
Examples from his page:
Function.prototype.method = function (name, func) {
this.prototype[name] = func;
return this;
};
Effect? It will allow you to add methods in more elegant way:
function Parenizor(value) {
this.setValue(value);
}
Parenizor.method('setValue', function (value) {
this.value = value;
return this;
});
I also recommend his videos:
Advanced JavaScript.
You can find more videos on his page: http://javascript.crockford.com/
In John Reisig book you can find many examples from Douglas Crockfor's website.

Because I will not admit the YUI/Crockford factory plan and because I like to keep things self contained and extensible this is my variation:
function Person(params)
{
this.name = params.name || defaultnamevalue;
this.role = params.role || defaultrolevalue;
if(typeof(this.speak)=='undefined') //guarantees one time prototyping
{
Person.prototype.speak = function() {/* do whatever */};
}
}
var Robert = new Person({name:'Bob'});
where ideally the typeof test is on something like the first method prototyped

If you're going for simple, you can avoid the "new" keyword entirely and just use factory methods. I prefer this, sometimes, because I like using JSON to create objects.
function getSomeObj(var1, var2){
var obj = {
instancevar1: var1,
instancevar2: var2,
someMethod: function(param)
{
//stuff;
}
};
return obj;
}
var myobj = getSomeObj("var1", "var2");
myobj.someMethod("bla");
I'm not sure what the performance hit is for large objects, though.

var Student = (function () {
function Student(firstname, lastname) {
this.firstname = firstname;
this.lastname = lastname;
this.fullname = firstname + " " + lastname;
}
Student.prototype.sayMyName = function () {
return this.fullname;
};
return Student;
}());
var user = new Student("Jane", "User");
var user_fullname = user.sayMyName();
Thats the way TypeScript compiles class with constructor to JavaScript.

The simple way is:
function Foo(a) {
var that=this;
function privateMethod() { .. }
// public methods
that.add = function(b) {
return a + b;
};
that.avg = function(b) {
return that.add(b) / 2; // calling another public method
};
}
var x = new Foo(10);
alert(x.add(2)); // 12
alert(x.avg(20)); // 15
The reason for that is that this can be bound to something else if you give a method as an event handler, so you save the value during instantiation and use it later.
Edit: it's definitely not the best way, just a simple way. I'm waiting for good answers too!

You probably want to create a type by using the Folding Pattern:
// Here is the constructor section.
var myType = function () {
var N = {}, // Enclosed (private) members are here.
X = this; // Exposed (public) members are here.
(function ENCLOSED_FIELDS() {
N.toggle = false;
N.text = '';
}());
(function EXPOSED_FIELDS() {
X.count = 0;
X.numbers = [1, 2, 3];
}());
// The properties below have access to the enclosed fields.
// Careful with functions exposed within the closure of the
// constructor, each new instance will have it's own copy.
(function EXPOSED_PROPERTIES_WITHIN_CONSTRUCTOR() {
Object.defineProperty(X, 'toggle', {
get: function () {
var before = N.toggle;
N.toggle = !N.toggle;
return before;
}
});
Object.defineProperty(X, 'text', {
get: function () {
return N.text;
},
set: function (value) {
N.text = value;
}
});
}());
};
// Here is the prototype section.
(function PROTOTYPE() {
var P = myType.prototype;
(function EXPOSED_PROPERTIES_WITHIN_PROTOTYPE() {
Object.defineProperty(P, 'numberLength', {
get: function () {
return this.numbers.length;
}
});
}());
(function EXPOSED_METHODS() {
P.incrementNumbersByCount = function () {
var i;
for (i = 0; i < this.numbers.length; i++) {
this.numbers[i] += this.count;
}
};
P.tweak = function () {
if (this.toggle) {
this.count++;
}
this.text = 'tweaked';
};
}());
}());
That code will give you a type called myType. It will have internal private fields called toggle and text. It will also have these exposed members: the fields count and numbers; the properties toggle, text and numberLength; the methods incrementNumbersByCount and tweak.
The Folding Pattern is fully detailed here:
Javascript Folding Pattern

Code golf for #liammclennan's answer.
var Animal = function (args) {
return {
name: args.name,
getName: function () {
return this.name; // member access
},
callGetName: function () {
return this.getName(); // method call
}
};
};
var cat = Animal({ name: 'tiger' });
console.log(cat.callGetName());

MooTools (My Object Oriented Tools) is centered on the idea of classes. You can even extend and implement with inheritance.
When mastered, it makes for ridiculously reusable, powerful javascript.

Object Based Classes with Inheritence
var baseObject =
{
// Replication / Constructor function
new : function(){
return Object.create(this);
},
aProperty : null,
aMethod : function(param){
alert("Heres your " + param + "!");
},
}
newObject = baseObject.new();
newObject.aProperty = "Hello";
anotherObject = Object.create(baseObject);
anotherObject.aProperty = "There";
console.log(newObject.aProperty) // "Hello"
console.log(anotherObject.aProperty) // "There"
console.log(baseObject.aProperty) // null
Simple, sweet, and gets 'er done.

Based on the example of Triptych, this might even be simpler:
// Define a class and instantiate it
var ThePerson = new function Person(name, gender) {
// Add class data members
this.name = name;
this.gender = gender;
// Add class methods
this.hello = function () { alert('Hello, this is ' + this.name); }
}("Bob", "M"); // this instantiates the 'new' object
// Use the object
ThePerson.hello(); // alerts "Hello, this is Bob"
This only creates a single object instance, but is still useful if you want to encapsulate a bunch of names for variable and methods in a class. Normally there would not be the "Bob, M" arguments to the constructor, for example if the methods would be calls to a system with its own data, such as a database or network.
I am still too new with JS to see why this does not use the prototype thing.

A base
function Base(kind) {
this.kind = kind;
}
A class
// Shared var
var _greeting;
(function _init() {
Class.prototype = new Base();
Class.prototype.constructor = Class;
Class.prototype.log = function() { _log.apply(this, arguments); }
_greeting = "Good afternoon!";
})();
function Class(name, kind) {
Base.call(this, kind);
this.name = name;
}
// Shared function
function _log() {
console.log(_greeting + " Me name is " + this.name + " and I'm a " + this.kind);
}
Action
var c = new Class("Joe", "Object");
c.log(); // "Good afternoon! Me name is Joe and I'm a Object"

JavaScript is object-oriented, but it's radically different than other OOP languages like Java, C# or C++. Don't try to understand it like that. Throw that old knowledge out and start anew. JavaScript needs a different thinking.
I'd suggest to get a good manual or something on the subject. I myself found ExtJS Tutorials the best for me, although I haven't used the framework before or after reading it. But it does give a good explanation about what is what in JavaScript world. Sorry, it seems that that content has been removed. Here's a link to archive.org copy instead. Works today. :P

//new way using this and new
function Persons(name) {
this.name = name;
this.greeting = function() {
alert('Hi! I\'m ' + this.name + '.');
};
}
var gee=new Persons("gee");
gee.greeting();
var gray=new Persons("gray");
gray.greeting();
//old way
function createPerson(name){
var obj={};
obj.name=name;
obj.greeting = function(){
console.log("hello I am"+obj.name);
};
return obj;
}
var gita=createPerson('Gita');
gita.greeting();

How to create converting constructor in javascript? [duplicate]

I prefer to use OOP in large scale projects like the one I'm working on right now. I need to create several classes in JavaScript but, if I'm not mistaken, there are at least a couple of ways to go about doing that. What would be the syntax and why would it be done in that way?
I would like to avoid using third-party libraries - at least at first.
Looking for other answers, I found the article Object-Oriented Programming with JavaScript, Part I: Inheritance - Doc JavaScript that discusses object-oriented programming in JavaScript. Is there a better way to do inheritance?

Here's the way to do it without using any external libraries:
// Define a class like this
function Person(name, gender){
// Add object properties like this
this.name = name;
this.gender = gender;
}
// Add methods like this. All Person objects will be able to invoke this
Person.prototype.speak = function(){
alert("Howdy, my name is" + this.name);
};
// Instantiate new objects with 'new'
var person = new Person("Bob", "M");
// Invoke methods like this
person.speak(); // alerts "Howdy, my name is Bob"
Now the real answer is a whole lot more complex than that. For instance, there is no such thing as classes in JavaScript. JavaScript uses a prototype-based inheritance scheme.
In addition, there are numerous popular JavaScript libraries that have their own style of approximating class-like functionality in JavaScript. You'll want to check out at least Prototype and jQuery.
Deciding which of these is the "best" is a great way to start a holy war on Stack Overflow. If you're embarking on a larger JavaScript-heavy project, it's definitely worth learning a popular library and doing it their way. I'm a Prototype guy, but Stack Overflow seems to lean towards jQuery.
As far as there being only "one way to do it", without any dependencies on external libraries, the way I wrote is pretty much it.

The best way to define a class in JavaScript is to not define a class.
Seriously.
There are several different flavors of object-orientation, some of them are:
class-based OO (first introduced by Smalltalk)
prototype-based OO (first introduced by Self)
multimethod-based OO (first introduced by CommonLoops, I think)
predicate-based OO (no idea)
And probably others I don't know about.
JavaScript implements prototype-based OO. In prototype-based OO, new objects are created by copying other objects (instead of being instantiated from a class template) and methods live directly in objects instead of in classes. Inheritance is done via delegation: if an object doesn't have a method or property, it is looked up on its prototype(s) (i.e. the object it was cloned from), then the prototype's prototypes and so on.
In other words: there are no classes.
JavaScript actually has a nice tweak of that model: constructors. Not only can you create objects by copying existing ones, you can also construct them "out of thin air", so to speak. If you call a function with the new keyword, that function becomes a constructor and the this keyword will not point to the current object but instead to a newly created "empty" one. So, you can configure an object any way you like. In that way, JavaScript constructors can take on one of the roles of classes in traditional class-based OO: serving as a template or blueprint for new objects.
Now, JavaScript is a very powerful language, so it is quite easy to implement a class-based OO system within JavaScript if you want to. However, you should only do this if you really have a need for it and not just because that's the way Java does it.

ES2015 Classes
In the ES2015 specification, you can use the class syntax which is just sugar over the prototype system.
class Person {
constructor(name) {
this.name = name;
}
toString() {
return `My name is ${ this.name }.`;
}
}
class Employee extends Person {
constructor(name, hours) {
super(name);
this.hours = hours;
}
toString() {
return `${ super.toString() } I work ${ this.hours } hours.`;
}
}
Benefits
The main benefit is that static analysis tools find it easier to target this syntax. It is also easier for others coming from class-based languages to use the language as a polyglot.
Caveats
Be wary of its current limitations. To achieve private properties, one must resort to using Symbols or WeakMaps. In future releases, classes will most likely be expanded to include these missing features.
Support
Browser support isn't very good at the moment (supported by nearly everyone except IE), but you can use these features now with a transpiler like Babel.
Resources
Classes in ECMAScript 6 (final semantics)
What? Wait. Really? Oh no! (a post about ES6 classes and privacy)
Compatibility Table – Classes
Babel – Classes

I prefer to use Daniel X. Moore's {SUPER: SYSTEM}. This is a discipline that provides benefits such as true instance variables, trait based inheritance, class hierarchies and configuration options. The example below illustrates the use of true instance variables, which I believe is the biggest advantage. If you don't need instance variables and are happy with only public or private variables then there are probably simpler systems.
function Person(I) {
I = I || {};
Object.reverseMerge(I, {
name: "McLovin",
age: 25,
homeState: "Hawaii"
});
return {
introduce: function() {
return "Hi I'm " + I.name + " and I'm " + I.age;
}
};
}
var fogel = Person({
age: "old enough"
});
fogel.introduce(); // "Hi I'm McLovin and I'm old enough"
Wow, that's not really very useful on it's own, but take a look at adding a subclass:
function Ninja(I) {
I = I || {};
Object.reverseMerge(I, {
belt: "black"
});
// Ninja is a subclass of person
return Object.extend(Person(I), {
greetChallenger: function() {
return "In all my " + I.age + " years as a ninja, I've never met a challenger as worthy as you...";
}
});
}
var resig = Ninja({name: "John Resig"});
resig.introduce(); // "Hi I'm John Resig and I'm 25"
Another advantage is the ability to have modules and trait based inheritance.
// The Bindable module
function Bindable() {
var eventCallbacks = {};
return {
bind: function(event, callback) {
eventCallbacks[event] = eventCallbacks[event] || [];
eventCallbacks[event].push(callback);
},
trigger: function(event) {
var callbacks = eventCallbacks[event];
if(callbacks && callbacks.length) {
var self = this;
callbacks.forEach(function(callback) {
callback(self);
});
}
},
};
}
An example of having the person class include the bindable module.
function Person(I) {
I = I || {};
Object.reverseMerge(I, {
name: "McLovin",
age: 25,
homeState: "Hawaii"
});
var self = {
introduce: function() {
return "Hi I'm " + I.name + " and I'm " + I.age;
}
};
// Including the Bindable module
Object.extend(self, Bindable());
return self;
}
var person = Person();
person.bind("eat", function() {
alert(person.introduce() + " and I'm eating!");
});
person.trigger("eat"); // Blasts the alert!
Disclosure: I am Daniel X. Moore and this is my {SUPER: SYSTEM}. It is the best way to define a class in JavaScript.

var Animal = function(options) {
var name = options.name;
var animal = {};
animal.getName = function() {
return name;
};
var somePrivateMethod = function() {
};
return animal;
};
// usage
var cat = Animal({name: 'tiger'});

Following are the ways to create objects in javascript, which I've used so far
Example 1:
obj = new Object();
obj.name = 'test';
obj.sayHello = function() {
console.log('Hello '+ this.name);
}
Example 2:
obj = {};
obj.name = 'test';
obj.sayHello = function() {
console.log('Hello '+ this.name);
}
obj.sayHello();
Example 3:
var obj = function(nameParam) {
this.name = nameParam;
}
obj.prototype.sayHello = function() {
console.log('Hello '+ this.name);
}
Example 4: Actual benefits of Object.create(). please refer [this link]
var Obj = {
init: function(nameParam) {
this.name = nameParam;
},
sayHello: function() {
console.log('Hello '+ this.name);
}
};
var usrObj = Object.create(Obj); // <== one level of inheritance
usrObj.init('Bob');
usrObj.sayHello();
Example 5 (customised Crockford's Object.create):
Object.build = function(o) {
var initArgs = Array.prototype.slice.call(arguments,1)
function F() {
if((typeof o.init === 'function') && initArgs.length) {
o.init.apply(this,initArgs)
}
}
F.prototype = o
return new F()
}
MY_GLOBAL = {i: 1, nextId: function(){return this.i++}} // For example
var userB = {
init: function(nameParam) {
this.id = MY_GLOBAL.nextId();
this.name = nameParam;
},
sayHello: function() {
console.log('Hello '+ this.name);
}
};
var bob = Object.build(userB, 'Bob'); // Different from your code
bob.sayHello();
To keep answer updated with ES6/ ES2015
A class is defined like this:
class Person {
constructor(strName, numAge) {
this.name = strName;
this.age = numAge;
}
toString() {
return '((Class::Person) named ' + this.name + ' & of age ' + this.age + ')';
}
}
let objPerson = new Person("Bob",33);
console.log(objPerson.toString());

I think you should read Douglas Crockford's Prototypal Inheritance in JavaScript and Classical Inheritance in JavaScript.
Examples from his page:
Function.prototype.method = function (name, func) {
this.prototype[name] = func;
return this;
};
Effect? It will allow you to add methods in more elegant way:
function Parenizor(value) {
this.setValue(value);
}
Parenizor.method('setValue', function (value) {
this.value = value;
return this;
});
I also recommend his videos:
Advanced JavaScript.
You can find more videos on his page: http://javascript.crockford.com/
In John Reisig book you can find many examples from Douglas Crockfor's website.

Because I will not admit the YUI/Crockford factory plan and because I like to keep things self contained and extensible this is my variation:
function Person(params)
{
this.name = params.name || defaultnamevalue;
this.role = params.role || defaultrolevalue;
if(typeof(this.speak)=='undefined') //guarantees one time prototyping
{
Person.prototype.speak = function() {/* do whatever */};
}
}
var Robert = new Person({name:'Bob'});
where ideally the typeof test is on something like the first method prototyped

If you're going for simple, you can avoid the "new" keyword entirely and just use factory methods. I prefer this, sometimes, because I like using JSON to create objects.
function getSomeObj(var1, var2){
var obj = {
instancevar1: var1,
instancevar2: var2,
someMethod: function(param)
{
//stuff;
}
};
return obj;
}
var myobj = getSomeObj("var1", "var2");
myobj.someMethod("bla");
I'm not sure what the performance hit is for large objects, though.

var Student = (function () {
function Student(firstname, lastname) {
this.firstname = firstname;
this.lastname = lastname;
this.fullname = firstname + " " + lastname;
}
Student.prototype.sayMyName = function () {
return this.fullname;
};
return Student;
}());
var user = new Student("Jane", "User");
var user_fullname = user.sayMyName();
Thats the way TypeScript compiles class with constructor to JavaScript.

The simple way is:
function Foo(a) {
var that=this;
function privateMethod() { .. }
// public methods
that.add = function(b) {
return a + b;
};
that.avg = function(b) {
return that.add(b) / 2; // calling another public method
};
}
var x = new Foo(10);
alert(x.add(2)); // 12
alert(x.avg(20)); // 15
The reason for that is that this can be bound to something else if you give a method as an event handler, so you save the value during instantiation and use it later.
Edit: it's definitely not the best way, just a simple way. I'm waiting for good answers too!

You probably want to create a type by using the Folding Pattern:
// Here is the constructor section.
var myType = function () {
var N = {}, // Enclosed (private) members are here.
X = this; // Exposed (public) members are here.
(function ENCLOSED_FIELDS() {
N.toggle = false;
N.text = '';
}());
(function EXPOSED_FIELDS() {
X.count = 0;
X.numbers = [1, 2, 3];
}());
// The properties below have access to the enclosed fields.
// Careful with functions exposed within the closure of the
// constructor, each new instance will have it's own copy.
(function EXPOSED_PROPERTIES_WITHIN_CONSTRUCTOR() {
Object.defineProperty(X, 'toggle', {
get: function () {
var before = N.toggle;
N.toggle = !N.toggle;
return before;
}
});
Object.defineProperty(X, 'text', {
get: function () {
return N.text;
},
set: function (value) {
N.text = value;
}
});
}());
};
// Here is the prototype section.
(function PROTOTYPE() {
var P = myType.prototype;
(function EXPOSED_PROPERTIES_WITHIN_PROTOTYPE() {
Object.defineProperty(P, 'numberLength', {
get: function () {
return this.numbers.length;
}
});
}());
(function EXPOSED_METHODS() {
P.incrementNumbersByCount = function () {
var i;
for (i = 0; i < this.numbers.length; i++) {
this.numbers[i] += this.count;
}
};
P.tweak = function () {
if (this.toggle) {
this.count++;
}
this.text = 'tweaked';
};
}());
}());
That code will give you a type called myType. It will have internal private fields called toggle and text. It will also have these exposed members: the fields count and numbers; the properties toggle, text and numberLength; the methods incrementNumbersByCount and tweak.
The Folding Pattern is fully detailed here:
Javascript Folding Pattern

Code golf for #liammclennan's answer.
var Animal = function (args) {
return {
name: args.name,
getName: function () {
return this.name; // member access
},
callGetName: function () {
return this.getName(); // method call
}
};
};
var cat = Animal({ name: 'tiger' });
console.log(cat.callGetName());

MooTools (My Object Oriented Tools) is centered on the idea of classes. You can even extend and implement with inheritance.
When mastered, it makes for ridiculously reusable, powerful javascript.

Object Based Classes with Inheritence
var baseObject =
{
// Replication / Constructor function
new : function(){
return Object.create(this);
},
aProperty : null,
aMethod : function(param){
alert("Heres your " + param + "!");
},
}
newObject = baseObject.new();
newObject.aProperty = "Hello";
anotherObject = Object.create(baseObject);
anotherObject.aProperty = "There";
console.log(newObject.aProperty) // "Hello"
console.log(anotherObject.aProperty) // "There"
console.log(baseObject.aProperty) // null
Simple, sweet, and gets 'er done.

Based on the example of Triptych, this might even be simpler:
// Define a class and instantiate it
var ThePerson = new function Person(name, gender) {
// Add class data members
this.name = name;
this.gender = gender;
// Add class methods
this.hello = function () { alert('Hello, this is ' + this.name); }
}("Bob", "M"); // this instantiates the 'new' object
// Use the object
ThePerson.hello(); // alerts "Hello, this is Bob"
This only creates a single object instance, but is still useful if you want to encapsulate a bunch of names for variable and methods in a class. Normally there would not be the "Bob, M" arguments to the constructor, for example if the methods would be calls to a system with its own data, such as a database or network.
I am still too new with JS to see why this does not use the prototype thing.

A base
function Base(kind) {
this.kind = kind;
}
A class
// Shared var
var _greeting;
(function _init() {
Class.prototype = new Base();
Class.prototype.constructor = Class;
Class.prototype.log = function() { _log.apply(this, arguments); }
_greeting = "Good afternoon!";
})();
function Class(name, kind) {
Base.call(this, kind);
this.name = name;
}
// Shared function
function _log() {
console.log(_greeting + " Me name is " + this.name + " and I'm a " + this.kind);
}
Action
var c = new Class("Joe", "Object");
c.log(); // "Good afternoon! Me name is Joe and I'm a Object"

JavaScript is object-oriented, but it's radically different than other OOP languages like Java, C# or C++. Don't try to understand it like that. Throw that old knowledge out and start anew. JavaScript needs a different thinking.
I'd suggest to get a good manual or something on the subject. I myself found ExtJS Tutorials the best for me, although I haven't used the framework before or after reading it. But it does give a good explanation about what is what in JavaScript world. Sorry, it seems that that content has been removed. Here's a link to archive.org copy instead. Works today. :P

//new way using this and new
function Persons(name) {
this.name = name;
this.greeting = function() {
alert('Hi! I\'m ' + this.name + '.');
};
}
var gee=new Persons("gee");
gee.greeting();
var gray=new Persons("gray");
gray.greeting();
//old way
function createPerson(name){
var obj={};
obj.name=name;
obj.greeting = function(){
console.log("hello I am"+obj.name);
};
return obj;
}
var gita=createPerson('Gita');
gita.greeting();

Trying simple approach to OPP inheritance in Javascript (ES5)

Just for the sake of curiosity, I was playing with prototypal inheritance and OOP inheritance in Javascript. Most results involve emulating 'Class' and 'extends' concepts with functions, while others use the prototype and constructors.
I wrote this code:
function Warrior(weaponName) {
var weapon = weaponName;
this.getWeapon = function() {
return weapon;
};
this.setWeapon = function(value) {
weapon = value;
};
this.displayInfo = function() {
return {
"weapon": this.getWeapon(),
};
};
}
function Archer() {
var accuracy = "86%";
this.parent = Archer.prototype; // Inheritance workaround
this.getAccuracy = function() {
return accuracy;
};
this.setAccuracy = function(value) {
accuracy = value;
};
this.displayInfo = function() {
var form = this.parent.displayInfo();
form.accuracy = this.getAccuracy();
return form;
};
}
Archer.prototype = new Warrior("bow");
var w = new Warrior("sword");
var a = new Archer();
console.log(w.displayInfo());
console.log(a.displayInfo());
I made this so when displaying the information from the Warrior class, it shows the object as
{ weapon: "sword" }
And when the information from Archer is shown, the object is:
{ weapon: "sword", accuracy: "86%" }
The "subclass" is taking information from the "superclass" and adding to it. Calling "getWeapon()" or "setWeapon" from Archer also works. The chain goes on without problems, even when I add a third class "Kyudoka" that extends "Archer" and has it's own properties as well.
But comparing to the more complex code I found while researching, I feel this could be a naive implementation (the "Inheritance workaround" line) and I'm missing something (considering that JS has a lot of subtlety).
This is a theorical question, I'm not using this code in any system.

There are mainly 3 kinds of inheritance in javascript, according to the book Javascript the Good Parts: Pseudoclassical, Prototypal and Functional.
The one you just posted would fit under the Pseudoclassical inheritance, where you emulate a Class behaviour using constructor functions.
I find more useful and flexible the Functional pattern, which allows you to protect your variables (make them private).
var constructor = function (spec, my) {
var that, other private instance variables;
my = my || {};
//Add shared variables and functions to my
that = a new object;
//Add privileged methods to that
return that;
}
Prototypal is basically having your objects inherit directly from other useful object, which would be something like having them (the useful objects) as your new object constructor prototype.
Object.beget = function (o) {
var F = function () {};
F.prototype = o;
return new F();
};
var a = {}
//Add shared variables to a
var b = Object.beget(a);
//Add new methods to b
That are many considerations to each of the patterns, for instance Crockford says in his book "The functional pattern has a great deal of flexibility. It requires less effort than the pseudoclassical pattern,
and gives us better encapsulation and information hiding and access to super methods.", but I've also seen articles arguing the other way around, such as this http://bolinfest.com/javascript/inheritance.php
EDIT ------
In case you might want to know different aproaches to reaching super methods, in the Functional pattern you can do the following:
Function.prototype.method = function (name, func) {
this.prototype[name] = func;
return this;
};
Object.method('superior', function (name) {
var that = this,
method = that[name];
return function ( ) {
return method.apply(that, arguments);
};
});
var archer = function (spec, accuracy) {
var that = warrior(spec),
super_displayInfo = that.superior('displayInfo');
that.getAccuracy = function() {
return accuracy;
};
that.setAccuracy = function(value) {
accuracy = value;
};
that.displayInfo = function (n) {
var form = super_displayInfo()
form.accuracy = that.getAccuracy();
return form;
};
return that;
};

Put the functions on the prototype...
function Warrior(weaponName) {
this.weapon = weaponName;
}
Warrior.prototype = {
getWeapon : function() {
return this.weapon;
},
setWeapon : function(value) {
this.weapon = value;
},
displayInfo : function() {
return { "weapon" : this.getWeapon() };
}
};
//----------------------------------
function Archer(weaponName) {
Warrior.call(this, weaponName);
this.accuracy = "86%";
}
Archer.prototype = Object.create(Warrior.prototype);
Archer.prototype.constructor = Archer;
Archer.prototype.getAccuracy = function() {
return this.accuracy;
};
Archer.prototype.setAccuracy = function(value) {
this.accuracy = value;
};
Archer.prototype.displayInfo = function() {
return "weapon: " + this.getWeapon() + ", accuracy: " + this.getAccuracy();
};
//----------------------------------
var w = new Warrior("sword");
var a = new Archer("axe");
console.log(w.displayInfo()); // Object {weapon: "sword"}
console.log(a.displayInfo()); // weapon: axe, accuracy: 86%
Edit: fixed recursion

Differences Between Hooking a Function onto Prototype or Not

What is the differences between:
function Gandalf() {
this.color = 'grey';
}
Gandalf.prototype.comeBack = function() {
this.color = 'white';
}
And:
function Gandalf() {
this.color = 'grey';
this.comeBack = function() {
this.color = 'white';
return this;
};
}
And under which circumstances should I hook the method onto the prototype, or not?

Alright Agent Kay, I'll approach this question in a different way than Esailija did. Let's begin with simple objects. For example say you already have an object called gandalf:
var gandalf = {
color: "grey",
comeBack: function () {
this.color = "white";
return this;
}
};
There are no constructors in this code. Hence this code is easy to understand. Am I right or am I right?
Alright, now I'm going to do something awesome. I'll create radagast from gandalf:
var radagast = Object.create(gandalf);
radagast.color = "brown";
What's happening here? Let's break it up:
We create a new object called radagast from gandalf using Object.create. Hence radagast inherits from gandalf.
We set the color of radagast to brown instead of grey.
To make it even more simple imagine you and I had the following conversation:
I: Hey Agent Kay, I met Radagast yesterday.
U: Who's Radagast?
I: Hmm... do you know who's Gandalf?
U: Yes, I do.
I: Well Radagast is just like Gandalf except that he's brown instead of white.
This is exactly how inheritance works in JavaScript. You see JavaScript has prototypal inheritance. In prototypal inheritance objects inherits from other objects. In this case radagast inherited from gandalf.
Now they way prototypal inheritance is usually implemented in JavaScript is weird. I call it the constructor pattern of prototypal inheritance. For example, take your code:
function Gandalf() {
this.color = "grey";
}
Gandalf.prototype.comeBack = function() {
this.color = "white";
return this;
};
Now when you create an instance of Gandalf what object does the instance inherit from? It inherits from Gandalf.prototype:
var gandalf = new Gandalf;
alert(Object.getPrototypeOf(gandalf) === Gandalf.prototype); // true
What's happening when you say new Gandalf is:
var gandalf = Object.create(Gandalf.prototype);
Gandalf.call(gandalf);
If you expand Gandalf.call(gandalf) the you get:
var gandalf = Object.create(Gandalf.prototype);
gandalf.color = "grey";
Now take your second example:
function Gandalf() {
this.color = "grey";
this.comeBack = function() {
this.color = "white";
return this;
};
}
In this case when you create an instance of Gandalf you're essentially doing this:
var gandalf = Object.create(Gandalf.prototype);
gandalf.color = "grey";
gandalf.comeBack = function () {
this.color = "white";
return this;
};
Hence every time you create a new Gandalf you create a new function comeBack. Thus if you call new Gandalf 10 times you'll have 10 different comeBack functions as well.
Compared to this in the first example since comeBack is defined on Gandalf.prototype, every time we call new Gandalf we get a new object which inherits from Gandalf.prototype. Hence there's only one comeBack function which is shared amongst all instances of Gandalf. Isn't that better?
Essentially think of your first example like this:
var gandalfPrototype = {
create: function () {
var gandalf = Object.create(this);
gandalf.color = "grey";
return gandalf;
},
comeBack: function () {
this.color = "white";
return this;
}
};
var gandalf = gandalfPrototype.create(); // there's only one comeBack function
Similarly your second example is equivalent to this:
var gandalfPrototype = {
create: function () {
var gandalf = Object.create(this);
gandalf.color = "grey";
gandalf.comeBack = function () {
this.color = "white";
return this;
};
return gandalf;
}
};
var gandalf = gandalfPrototype.create(); // there's 1 comeBack for each instance
Remember that when you use new before a function call you're actually inheriting from the prototype of the function. Not the function itself.
Finally I would like to say (because I'm a big fan of J.R.R. Tolkien) that this is the way I would write your code:
var wizard = {
create: function (color) {
var wizard = Object.create(this);
wizard.color = color;
return wizard;
}
};
var gandalf = wizard.create("grey");
gandalf.comeBack = function () {
this.color = "white";
return this;
};
var saruman = wizard.create("white");
var radagast = wizard.create("brown");
Thank you for reading my answer.

The reason to put it on prototype is because every object created can use the same function object (functions are merely callable objects), they only need different identity and data. But in the second case you are creating unique function objects for each object even though they can use the same function object.
Since you seem to know PHP, the difference would be similar in PHP:
class Gandalf {
public $color = "grey";
public function comeBack() {
$this->color = "white";
}
}
class Gandalf {
public $color = "grey";
//Create the method inside constructor everytime
public function __construct() {
$this->comeBack = function() {
$this->color = "white";
return $this;
}->bindTo($this, $this);
}
}
It is hard to say when to use the other when performance is not a concern. Personally the
obfuscation of the constructor function and the additional indentation level are enough for me to prefer the prototype.

To answer:
under which circumstances should I hook the method onto the prototype, or not?
If you have a function that need to access private vars of an object created with a constructor function, it needs to be inside constructor function.
function Gandalf() {
var age = '30000'; //approximate
this.alertAge1 = function() {
alert( age );
};
}
Gandalf.prototype.alertAge2 = function() {
// age not visible from here
};