Prototypal object creation in JavaScript is claimed to be powerful (I hear it is efficient and if used correctly very expressive). But for some reason I find that it trips me up much more often than it helps me.
The main problem I have with patterns for object creation involving prototype is that there is no way to bypass the need for this. The main reason is that objects that are anything beyond very primitive, for example objects that populate themselves through asynchronous API calls, this breaks down due to change of scope.
So, I use prototypal object creation for objects that I know everything about from the beginning.
But for objects that need to do for example API calls to keep themselves up to date I completely skip prototype and use straight up object literals.
When I feel the need for extending one of these objects, I have used parasitic inheritence:
var ROOT = ROOT || {};
ROOT.Parent = function () {
var self = {
func1 : function () {
alert("func1")
};
}
return self;
};
ROOT.Child = function () {
var self = ROOT.Parent(); // This is the parasitizing
self.func2 = function () {
alert("func2")
};
return self;
};
var myChild = ROOT.Child();
myChild.func1(); // alerts "func1"
myChild.func2(); // alerts "func2"
Using this pattern, I can reuse the code for func1 in the ROOT.Child object. However if I want to extend the code in func1 I have a problem. I.e if I want to call the code in the parents func1 and also my own func1 this pattern presents a challenge. I cannot do this:
ROOT.Child = function () {
var self = ROOT.Parent();
self.func1 = function () {
alert("func2")
};
};
Since this will completely replace the function. To solve this I have come up with the following solution (which you can also check out here: http://jsfiddle.net/pellepim/mAGUg/9/).
var ROOT = {};
/**
* This is the base function for Parasitic Inheritence
*/
ROOT.Inheritable = function () {
var self = {
/**
* takes the name of a function that should exist on "self", and
* rewires it so that it executes both the original function, and the method
* supplied as second parameter.
*/
extend : function (functionName, func) {
if (self.hasOwnProperty(functionName)) {
var superFunction = self[functionName];
self[functionName] = function () {
superFunction();
func();
};
}
},
/**
* Takes the name of a function and reassigns it to the function supplied
* as second parameter.
*/
replace : function (methodName, func) {
self[methodName] = func;
}
};
return self;
};
/**
* "Inherits" from ROOT.Inheritable
*/
ROOT.Action = function () {
var self = ROOT.Inheritable();
/**
* I intend to extend this method in an inheriting object
*/
self.methodToExtend = function () {
alert("I should be seen first, since I get extended");
};
/**
* I intend to replace this method in an inheriting object
*/
self.methodToReplace = function () {
alert("I should never be seen, since I get replaced.");
};
return self;
};
/**
* "Inherits" from ROOT.Action.
*/
ROOT.Task = function () {
var self = ROOT.Action();
self.extend('methodToExtend', function () {
alert("I successfully ran the extended code too.");
});
/**
* I know it is completely unecessary to have a replace method,
* I could just as easily just type self.methodToReplace = function () ...
* but I like that you see that you are actually replacing something.
*/
self.replace('methodToReplace', function () {
alert("I successfully replaced the \"super\" method.");
});
return self;
};
var task = ROOT.Task();
task.methodToExtend(); // I expect both the "base" and "child" method to run.
task.methodToReplace(); // I expect only the "child" method to run.
Ok, so I should ask a question. Am I completely off target here or am I on to something? What are the apparent drawbacks?
No, you're not off target. But you did not invent that wheel also. That type of ECMAscript inheritance became very famous with Doug Crockfords book Javascript: The good parts.
It is a nice pattern and uses closures nicely to keep things private and protected. However, it's still up to you which patterns you prefer (plain prototypal inheritance, pseudo-classical).
With ES5 and new possiblitys like Object.create() and Object.defineProperties(), Object.freeze() to name a few, we also have good ways to have protection and privacy with a more prototypal approach. Personally, I still prefer and like the pseudo classical way, using closures to do stuff.
The caveat still might be function-calls overhead which you generally can avoid using a plain prototypal inheritance. We need to make a whole lot more calls to get things properly done (if things grows). Still, closures are considered to be a little memory greedy and probably be a reason for leaks if we use them sloppy or forget to clean up references here and there. I don't have any reference for this now, but I strongly believe that the latest js engines are not much slower using closures like a lot.
Related
This is a question about performance and best practice.
Assuming I have a js object that encapsulates a large number of helper methods. The object is being treated as a static class, meaning it is never instantiated and all its methods are basically helper methods.
When using events and jQuery, the object's this scope keeps changing, and since it has a fairly large number of methods I am wondering what is best practice - saving this into _this at the beginning of each method or simply use the object name MyObject.
Over the years I've been doing both, when it comes to singelton/static objects, but I figured there must be just 1 best practice and it's about time to adopt the best approach.
My current research shows that the benefits that come with using _this instead of directly calling MyObject are mainly these two:
if the object's name changes, _this will always work
May be faster (although haven't seen performance testing results) since the browser stays in the same scope and does not need to find out the scope of MyObject every time.
Pros of using MyObject:
Less code to write.
Garbage collection management? (less variables to assign)
May be more readable for some developers (where multiple this apply)
Easier to refactor code since MyObject will always work
I would like to know if there is a way of globally saving _this (only inside the object's scope of course) and avoid assigning it at the beginning of each method. If not - are there other pros/cons that I am missing or is it considered bad practice to call the object name directly.
This is a simplified object for reference (real object has many more methods).
var MyObject = {
init: function() {
this.registerEvents();
//other stuff
},
registerEvents: function() {
this.registerOnSomeEvent();
//registering more events..
//...
},
registerOnSomeEvent: function() {
var _this = this;
jQuery('#someid').click(function() {
_this.doSomething();//option 1
MyObject.doSomething();//option 2
});
},
doSomething: function() {
//doing something...
}
}
MyObject.init();
Thank you for your help!
You can encapsulate the entire object in a closure to achieve this without specifiying _this on every function:
window.MyObject = (function () {
var self = {
init: function() {
self.registerEvents();
//other stuff
},
registerEvents: function() {
self.registerOnSomeEvent();
//registering more events..
//...
},
registerOnSomeEvent: function() {
jQuery('#someid').click(function() {
self.doSomething();//option 1
self.doSomething();//option 2
});
},
doSomething: function() {
//doing something...
}
};
self.init();
return self;
})();
I think your problem is that you go a very long way of painstakingly emulating something you should do instead.
const mySingleton = (function () {
// Instance stores a reference to the Singleton
var instance;
function init() {
// Singleton
// Private methods and variables
var privateVariable = "Im also private";
var privateRandomNumber = Math.random();
return {
// Public methods and variables
publicMethod: function () {
console.log( "The public can see me!" );
},
publicProperty: "I am also public",
get randomNumber() {
return privateRandomNumber;
}
};
function privateMethod(){
console.log( "I am private" );
}
};
return {
// Get the Singleton instance if one exists
// or create one if it doesn't
get instance() {
if ( !instance ) instance = init();
return instance;
}
};
})();
If you don't want to ever use the this context, never use inheritance and never have more than one instance just don't write those things as methods on an object, but rather declared, private methods in a singleton pattern (which is a revealing module pattern but with only a single instance)
Because as it is you basically make exactly that but you are revealing everything and you spam this hundreds and hundreds of times completely without any purpose. this isn't a constant by design. Don't use it as such.
I'm new to JavaScript and am trying to understand how to use namespaces to avoid naming conflicts. So far, the two most popular methods I've found for creating namespaces are these:
Method 1:
var MYAPPLICATION = {
calculateVat: function (base) {
return base * 1.21;
},
product: function (price) {
this.price = price;
this.getPrice = function(){
return this.price;
};
},
doCalculations: function () {
var p = new MYAPPLICATION.product(100);
alert(this.calculateVat(p.getPrice()));
}
}
Method 2:
var DED = (function() {
var private_var;
function private_method()
{
// do stuff here
}
return {
method_1 : function()
{
// do stuff here
},
method_2 : function()
{
// do stuff here
}
};
})();
Is the difference that the second method allows you to have private methods and variables, since only what is inside of the object being returned will be globally accessible? Which of these methods is best (or is there a better way)?
If you write an API for other people, I think method two is better. Example：jQuery.
In a web page, I prefer method one. Example：stackoverflow
In method two, you can not read and write functions and variables that is private, so if there is a bug, you can not read something by developer-tools for debug.
Second method is called 'module' pattern. Makes it comfortable for developers to use your code. Self-invoking function creates scope, so you only expose methods that you want to make public by returning object that contains references to those methods (public API). Those methods can have a lot of private helper functions and variables that you keep private for your own use. Most of the libraries are written this way. It's generally good to structure your library like that.
Here's a link to the website that explains it well : http://www.adequatelygood.com/JavaScript-Module-Pattern-In-Depth.html
First method is just the way to put all the related functions together. You can make those for personal use in your module. Example:
Calc.add(5,5), Calc.subtract(3,2), Calc.multiply(3,3);
add, subtract, multiply share same namespace because they are related.
I've got a browser addon I've been maintaining for 5 years, and I'd like to share some common code between the Firefox and Chrome versions.
I decided to go with the Javascript Module Pattern, and I'm running into a problem with, for example, loading browser-specific preferences, saving data, and other browser-dependent stuff.
What I'd like to do is have the shared code reference virtual, overrideable methods that could be implemented in the derived, browser-specific submodules.
Here's a quick example of what I've got so far, that I've tried in the Firebug console, using the Tight Augmentation method from the article I referenced:
var core = (function(core)
{
// PRIVATE METHODS
var over = function(){ return "core"; };
var foo = function() {
console.log(over());
};
// PUBLIC METHODS
core.over = over;
core.foo = foo;
return core;
}(core = core || {}));
var ff_specific = (function(base)
{
var old_over = base.over;
base.over = function() { return "ff_specific"; };
return base;
}(core));
core.foo();
ff_specific.foo();
Unfortunately, both calls to foo() seem to print "core", so I think I've got a fundamental misunderstanding of something.
Essentially, I'm wanting to be able to call:
get_preference(key)
set_preference(key, value)
load_data(key)
save_data(key, value)
and have each browser do their own thing. Is this possible? Is there a better way to do it?
In javascript functions have "lexical scope". This means that functions create their environment - scope when they are defined, not when they are executed. That's why you can't substitute "over" function later:
var over = function(){ return "core"; };
var foo = function() {
console.log(over());
};
//this closure over "over" function cannot be changed later
Furthermore you are "saying" that "over" should be private method of "core" and "ff_specific" should somehow extend "core" and change it (in this case the private method which is not intended to be overridden by design)
you never override your call to foo in the ff_specific code, and it refers directly to the private function over() (which never gets overridden), not to the function core.over() (which does).
The way to solve it based on your use case is to change the call to over() to be a call to core.over().
That said, you're really confusing yourself by reusing the names of things so much, imo. Maybe that's just for the example code. I'm also not convinced that you need to pass in core to the base function (just to the children).
Thanks for your help. I'd forgotten I couldn't reassign closures after they were defined. I did figure out a solution.
Part of the problem was just blindly following the example code from the article, which meant that the anonymous function to build the module was being called immediately (the reusing of names Paul mentioned). Not being able to reassign closures, even ones that I specifically made public, meant I couldn't even later pass it an object that would have its own methods, then check for them.
Here's what I wound up doing, and appears to work very well:
var ff_prefs = (function(ff_prefs)
{
ff_prefs.foo = function() { return "ff_prefs browser specific"; };
return ff_prefs;
}({}));
var chrome_prefs = (function(chrome_prefs)
{
chrome_prefs.foo = function() { return "chrome_prefs browser specific"; };
return chrome_prefs;
}({}));
var test_module = function(extern)
{
var test_module = {};
var talk = function() {
if(extern.foo)
{
console.log(extern.foo());
}
else
{
console.log("No external function!");
}
};
test_module.talk = talk;
return test_module;
};
var test_module_ff = new test_module(ff_prefs);
var test_module_chrome = new test_module(chrome_prefs);
var test_module_none = new test_module({});
test_module_ff.talk();
test_module_chrome.talk();
test_module_none.talk();
Before, it was running itself, then when the extension started, it would call an init() function, which it can still do. It's just no longer an anonymous function.
In Ruby I think you can call a method that hasn't been defined and yet capture the name of the method called and do processing of this method at runtime.
Can Javascript do the same kind of thing ?
method_missing does not fit well with JavaScript for the same reason it does not exist in Python: in both languages, methods are just attributes that happen to be functions; and objects often have public attributes that are not callable. Contrast with Ruby, where the public interface of an object is 100% methods.
What is needed in JavaScript is a hook to catch access to missing attributes, whether they are methods or not. Python has it: see the __getattr__ special method.
The __noSuchMethod__ proposal by Mozilla introduced yet another inconsistency in a language riddled with them.
The way forward for JavaScript is the Proxy mechanism (also in ECMAscript Harmony), which is closer to the Python protocol for customizing attribute access than to Ruby's method_missing.
The ruby feature that you are explaining is called "method_missing" http://rubylearning.com/satishtalim/ruby_method_missing.htm.
It's a brand new feature that is present only in some browsers like Firefox (in the spider monkey Javascript engine). In SpiderMonkey it's called "__noSuchMethod__" https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Object/NoSuchMethod
Please read this article from Yehuda Katz http://yehudakatz.com/2008/08/18/method_missing-in-javascript/ for more details about the upcoming implementation.
Not at the moment, no. There is a proposal for ECMAScript Harmony, called proxies, which implements a similar (actually, much more powerful) feature, but ECMAScript Harmony isn't out yet and probably won't be for a couple of years.
You can use the Proxy class.
var myObj = {
someAttr: 'foo'
};
var p = new Proxy(myObj, {
get: function (target, methodOrAttributeName) {
// target is the first argument passed into new Proxy, aka. target is myObj
// First give the target a chance to handle it
if (Object.keys(target).indexOf(methodOrAttributeName) !== -1) {
return target[methodOrAttributeName];
}
// If the target did not have the method/attribute return whatever we want
// Explicitly handle certain cases
if (methodOrAttributeName === 'specialPants') {
return 'trousers';
}
// return our generic method_missing function
return function () {
// Use the special "arguments" object to access a variable number arguments
return 'For show, myObj.someAttr="' + target.someAttr + '" and "'
+ methodOrAttributeName + '" called with: ['
+ Array.prototype.slice.call(arguments).join(',') + ']';
}
}
});
console.log(p.specialPants);
// outputs: trousers
console.log(p.unknownMethod('hi', 'bye', 'ok'));
// outputs:
// For show, myObj.someAttr="foo" and "unknownMethod" called with: [hi,bye,ok]
About
You would use p in place of myObj.
You should be careful with get because it intercepts all attribute requests of p. So, p.specialPants() would result in an error because specialPants returns a string and not a function.
What's really going on with unknownMethod is equivalent to the following:
var unk = p.unkownMethod;
unk('hi', 'bye', 'ok');
This works because functions are objects in javascript.
Bonus
If you know the number of arguments you expect, you can declare them as normal in the returned function.
eg:
...
get: function (target, name) {
return function(expectedArg1, expectedArg2) {
...
I've created a library for javascript that let you use method_missing in javascript: https://github.com/ramadis/unmiss
It uses ES6 Proxies to work. Here is an example using ES6 Class inheritance. However you can also use decorators to achieve the same results.
import { MethodMissingClass } from 'unmiss'
class Example extends MethodMissingClass {
methodMissing(name, ...args) {
console.log(`Method ${name} was called with arguments: ${args.join(' ')}`);
}
}
const instance = new Example;
instance.what('is', 'this');
> Method what was called with arguments: is this
No, there is no metaprogramming capability in javascript directly analogous to ruby's method_missing hook. The interpreter simply raises an Error which the calling code can catch but cannot be detected by the object being accessed. There are some answers here about defining functions at run time, but that's not the same thing. You can do lots of metaprogramming, changing specific instances of objects, defining functions, doing functional things like memoizing and decorators. But there's no dynamic metaprogramming of missing functions as there is in ruby or python.
I came to this question because I was looking for a way to fall through to another object if the method wasn't present on the first object. It's not quite as flexible as what your asking - for instance if a method is missing from both then it will fail.
I was thinking of doing this for a little library I've got that helps configure extjs objects in a way that also makes them more testable. I had seperate calls to actually get hold of the objects for interaction and thought this might be a nice way of sticking those calls together by effectively returning an augmented type
I can think of two ways of doing this:
Prototypes
You can do this using prototypes - as stuff falls through to the prototype if it isn't on the actual object. It seems like this wouldn't work if the set of functions you want drop through to use the this keyword - obviously your object wont know or care about stuff that the other one knows about.
If its all your own code and you aren't using this and constructors ... which is a good idea for lots of reasons then you can do it like this:
var makeHorse = function () {
var neigh = "neigh";
return {
doTheNoise: function () {
return neigh + " is all im saying"
},
setNeigh: function (newNoise) {
neigh = newNoise;
}
}
};
var createSomething = function (fallThrough) {
var constructor = function () {};
constructor.prototype = fallThrough;
var instance = new constructor();
instance.someMethod = function () {
console.log("aaaaa");
};
instance.callTheOther = function () {
var theNoise = instance.doTheNoise();
console.log(theNoise);
};
return instance;
};
var firstHorse = makeHorse();
var secondHorse = makeHorse();
secondHorse.setNeigh("mooo");
var firstWrapper = createSomething(firstHorse);
var secondWrapper = createSomething(secondHorse);
var nothingWrapper = createSomething();
firstWrapper.someMethod();
firstWrapper.callTheOther();
console.log(firstWrapper.doTheNoise());
secondWrapper.someMethod();
secondWrapper.callTheOther();
console.log(secondWrapper.doTheNoise());
nothingWrapper.someMethod();
//this call fails as we dont have this method on the fall through object (which is undefined)
console.log(nothingWrapper.doTheNoise());
This doesn't work for my use case as the extjs guys have not only mistakenly used 'this' they've also built a whole crazy classical inheritance type system on the principal of using prototypes and 'this'.
This is actually the first time I've used prototypes/constructors and I was slightly baffled that you can't just set the prototype - you also have to use a constructor. There is a magic field in objects (at least in firefox) call __proto which is basically the real prototype. it seems the actual prototype field is only used at construction time... how confusing!
Copying methods
This method is probably more expensive but seems more elegant to me and will also work on code that is using this (eg so you can use it to wrap library objects). It will also work on stuff written using the functional/closure style aswell - I've just illustrated it with this/constructors to show it works with stuff like that.
Here's the mods:
//this is now a constructor
var MakeHorse = function () {
this.neigh = "neigh";
};
MakeHorse.prototype.doTheNoise = function () {
return this.neigh + " is all im saying"
};
MakeHorse.prototype.setNeigh = function (newNoise) {
this.neigh = newNoise;
};
var createSomething = function (fallThrough) {
var instance = {
someMethod : function () {
console.log("aaaaa");
},
callTheOther : function () {
//note this has had to change to directly call the fallThrough object
var theNoise = fallThrough.doTheNoise();
console.log(theNoise);
}
};
//copy stuff over but not if it already exists
for (var propertyName in fallThrough)
if (!instance.hasOwnProperty(propertyName))
instance[propertyName] = fallThrough[propertyName];
return instance;
};
var firstHorse = new MakeHorse();
var secondHorse = new MakeHorse();
secondHorse.setNeigh("mooo");
var firstWrapper = createSomething(firstHorse);
var secondWrapper = createSomething(secondHorse);
var nothingWrapper = createSomething();
firstWrapper.someMethod();
firstWrapper.callTheOther();
console.log(firstWrapper.doTheNoise());
secondWrapper.someMethod();
secondWrapper.callTheOther();
console.log(secondWrapper.doTheNoise());
nothingWrapper.someMethod();
//this call fails as we dont have this method on the fall through object (which is undefined)
console.log(nothingWrapper.doTheNoise());
I was actually anticipating having to use bind in there somewhere but it appears not to be necessary.
Not to my knowledge, but you can simulate it by initializing the function to null at first and then replacing the implementation later.
var foo = null;
var bar = function() { alert(foo()); } // Appear to use foo before definition
// ...
foo = function() { return "ABC"; } /* Define the function */
bar(); /* Alert box pops up with "ABC" */
This trick is similar to a C# trick for implementing recursive lambdas, as described here.
The only downside is that if you do use foo before it's defined, you'll get an error for trying to call null as though it were a function, rather than a more descriptive error message. But you would expect to get some error message for using a function before it's defined.
I'm interesting in improving my javascript code to be properly OOP.... currently I tend to do something like this:
jQuery(document).ready(function () {
Page.form = (function () {
return {
//generate a new PDF
generatePDF: function () {
},
//Update the list of PDFs available for download
updatePDFDownloads: function () {
},
/*
* Field specific functionality
*/
field: (function () {
return {
//show the edit prompt
edit: function (id, name) {
},
//refresh the value of a field with the latest from the database
refresh: function (id) {
}
};
}())
};
}());
});
In the end it's just mainly organized functions I suppose... what's a good resource where I can learn to program javascript in an OOP manner, or what suggestions would you have for improving my current style of programming?
It seems like I should do a sort of model prototype and have my form object inherit from that prototype.
(I'm using jQuery instead of $ because of conflicts with prototypeJS)
Your question is quite broad so I don't think a complete answer is possible here. But here are a few points.
Regarding the code you have shown. You're jumping a couple of redundant hoops.
Unless you're accessing the DOM in some way, there is no need to wrap your code in jQuery(document).ready()
There is no need to return an object from a self calling anonymous function unless you're closing over some private functions or data
The object you have created can be created more simply (a good thing) like this
var Page = {
form: {
//generate a new PDF
generatePDF: function () {
},
//Update the list of PDFs available for download
updatePDFDownloads: function () {
},
/*
* Field specific functionality
*/
field: {
//show the edit prompt
edit: function (id, name) {
},
//refresh the value of a field with the latest from the database
refresh: function (id) {
}
}
}
};
It's easier to read and less confusing, only do things that buy you something. see cargo cult programming
Here's an example using a self calling anonymous function to create private members
var Obj = (function() {
privateFunction( param ) {
// do something with param
}
var privateVar = 10;
return {
// publicMethod has access to privateFunction and privateVar
publicMethod: function() {
return privateFunction( privateVar );
}
}
})();
The structure you have used, object literals are very good, as you say, at grouping a set of functions (methods) and properties. This is a kind of namespace. It is also a way of creating a Singleton. You may also want to create many objects of the same Class.
JavaScript doesn't have classes like traditional OO languages (I'll get to that) but at the simplest level it's very easy to create a 'template' for creating objects of a particular type. These 'templates' are normal functions called constructors.
// a constructor
// it creates a drink with a particular thirst quenchingness
function Drink( quenchingness ) {
this.quenchingness = quenchingness;
}
// all drinks created with the Drink constructor get the chill method
// which works on their own particular quenchingness
Drink.prototype.chill = function() {
this.quenchingness *= 2; //twice as thirst quenching
}
var orange = new Drink( 10 );
var beer = new Drink( 125 );
var i_will_have = ( orange.quenchingness > beer.quenchingness )
? orange
: beer; //beer
var beer2 = new Drink( 125 );
beer2.chill();
var i_will_have = ( beer2.quenchingness > beer.quenchingness )
? beer2
: beer; //beer2 - it's been chilled!
There's a lot to know about constructors. You'll have to search around. There are lots of examples on SO.
Inheritance, the foundation of OO, is not that intuitive in js because it is prototypal. I won't go into that here because you will more than likely not use js's native prototypal inheritance paradigm directly.
This is because there are libraries that mimic classical inheritance very effectively, Prototype (inheritance) or mootools (Class) for example. There are others.
Many say that inheritance is overused in OO and that you should favour composition and this brings me to what I initially set out to recommend when I started this rambling answer.
Design patterns in JavaScript are as useful as in any OO language and you should familiarise yourself with them
I recommend you read Pro JavaScript Design Patterns.
There, that's it
Some good sources for Object-Oriented JavaScript and JavaScript in general...
Online Articles
How to "properly" create a custom object in JavaScript?
https://developer.mozilla.org/en/Introduction_to_Object-Oriented_JavaScript
http://mckoss.com/jscript/object.htm
http://ejohn.org/blog/simple-javascript-inheritance/
JavaScript: How To Get Private, Privileged, Public And Static Members (Properties And Methods)
Books
JavaScript: The Good Parts - Douglas Crockford
Object-Oriented JavaScript - Stoyan Stefanov
I hope this helps.
Hristo
There isn't one correct way... Some people use a framework to define their object, I like to just extend prototype directly. Anyhow, I wanted to say that Oran Looney has some good posts on OO mechanics in JS:
http://oranlooney.com/classes-and-objects-javascript/
Its also worth looking at his other articles:
http://oranlooney.com/deep-copy-javascript/
http://oranlooney.com/functional-javascript/
The top 3 I suggest to read is
JavaScript and Object Oriented Programming (OOP)
Classical Inheritance in JavaScript
Prototypal Inheritance in JavaScript
Have a nice reading!
The code we are using follows this basic structure:
//Create and define Global NameSpace Object
( function(GlobalObject, $, undefined)
{
GlobalObject.Method = function()
{
///<summary></summary>
}
}) (GlobalObject = GlobalObject || {}, jQuery);
//New object for specific functionality
( function(Functionality.Events, $, undefined)
{
//Member Variables
var Variable; // (Used for) , (type)
// Initialize
GlobalObject.Functionality.Events.Init = function()
{
///<summary></summary>
}
// public method
this.PublicMethod = function(oParam)
{
///<summary></summary>
///<param type=""></param>
}
// protected method (typically define in global object, but can be made available from here)
GlobalObject.Functionality.ProtectedMethod = function()
{
///<summary></summary>
}
// internal method (typically define in global object, but can be made available from here)
GlobalObject.InternalMethod = function()
{
///<summary></summary>
}
// private method
var privateMethod = function()
{
///<summary></summary>
}
}) (GlobalObject.Funcitonality.Events = GlobalObject.Funcitonality.Events || {}, jQuery )
The strength to this is that it initializes the Global object automatically, allows you to maintain the intergrity of your code, and organizes each piece of functionality into a specific grouping by your definition. This structure is solid, presenting all of the basic syntactical things you would expect from OOP without the key words. Even setting up intelisense is possible with javascript, and then defining each peice and referencing them makes writing javascript cleaner and more manageable. Hope this layout helps!
I dont think it matters what language you use, good OOP is good OOP. I like to split up my concerns as much as possible by using an MVC architecture. Since JavaScript is very event based, I also use the observer design pattern mostly.
Heres a tutorial you can read about MVC using jQuery.