Is JavaScript object-oriented

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There have been some questions about whether or not JavaScript is an object-oriented language  Even a statement   just because a language has objects doesn t make it OO    Is JavaScript an object-oriented language

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JavaScript is a very good language to write object oriented web apps  It can support OOP because supports inheritance through prototyping also properties and methods  You can have polymorphism  encapsulation and many sub-classing paradigms

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The short answer is Yes  For more information   From Wikipedia      JavaScript is heavily object-based    Objects are associative arrays    augmented with prototypes  see below     Object property names are associative   array keys  obj x   10 and obj  x       10 are equivalent  the dot notation   being merely syntactic sugar    Properties and their values can be   added  changed  or deleted at   run-time  The properties of an object   can also be enumerated via a for   in   loop    Also  see this series of articles about OOP with Javascript

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Yes  it is  However  it doesn t support all of the features one would expect in an object oriented programming language lacking inheritance and polymorphism  This doesn t mean  however  that you cannot simulate these capabilities through the prototyping system that is avaialble to the language

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Javascript is not an object oriented language as typically considered  mainly due to lack of true inheritance  DUCK typing allows for a semi-true form of inheritance polymorphism along with the Object prototype allowing for complex function sharing  At its heart however the lack of inheritance leads to a weak polymorphism to take place since the DUCK typing will insist some object with the same attribute names are an instance of an Object which they were not intended to be used as  Thus adding attributes to random object transforms their type s base in a manner of speaking

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This is of course subjective and an academic question  Some people argue whether an OO language has to implement classes and inheritance  others write programs that change your life   -    But really  why should an OO language have to implement classes  I d think objects were the key components  How you create and then use them is another matter

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it is a good thread  Here s some resources i like   Most people start out with prototype  jquery  or one of the top 6 libs mootools  ExtJS  YUI   which have different object models   Prototype tries to replicate classical O-O as most people think of it   http   jquery com blog 2006 08 20 why-jquerys-philosophy-is-better   Here s a picture of prototypes and functions that i refer to a lot  http   www mollypages org misc js mp

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Is JavaScript object-oriented  Answer   Yes  It has objects which can contain data and methods that act upon that data  Objects can contain other objects   It does not have classes  but it does have constructors which do what classes do  including acting as containers for class variables and methods  It does not have class-oriented inheritance  but it does have prototype-oriented inheritance   The two main ways of building up object systems are by inheritance  is-a  and by aggregation  has-a   JavaScript does both  but its dynamic nature allows it to excel at aggregation  Some argue that JavaScript is not truly object oriented because it does not provide information hiding  That is  objects cannot have private variables and private methods  All members are public  But it turns out that JavaScript objects can have private variables and private methods   Click here now to find out how   Of course  few understand this because JavaScript is the world s most misunderstood programming language  Some argue that JavaScript is not truly object oriented because it does not provide inheritance  But it turns out that JavaScript supports not only classical inheritance  but other code reuse patterns as well  Sources   http   javascript crockford com javascript html

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The Microsoft Ajax Client Library makes it simple to implement OO in javascript  It supports inharitence  and interface implementation

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JavaScript is object-oriented  but is not a class-based object-oriented language like Java  C    C   etc  Class-based OOP languages are a subset of the larger family of OOP languages which also include prototype-based languages like JavaScript and Self

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Everything in javascript is an object - classes are objects  functions are objects  numbers are objects  objects objects objects  It s not as strict about typing as other languages  but it s definitely possible to write OOP JS

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Unlike most object-oriented languages  JavaScript  before ECMA 262 Edition 4  anyway  has no concept of classes  but prototypes  As such  it is indeed somewhat subjective whether to call it object-oriented or not    eliben  Wikipedia says object-based  That s not the same as object-oriented  In fact  their article on object-based distinguishes between object-oriented languages and prototype-based ones  explicitly calling JavaScript not object-oriented

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JavaScript is a prototype-based programming language  probably prototype-based scripting language is more correct definition   It employs cloning and not inheritance  A prototype-based programming language is a style of object-oriented programming without classes  While object-oriented programming languages encourages development focus on taxonomy and relationships  prototype-based programming languages encourages to focus on behavior first and then later classify   The term    object-oriented    was coined by Alan Kay in 1967  who explains it in 2003 to mean       only messaging  local retention and protection and hiding of state-process  and extreme late-binding of all things     source    In object-oriented programming  each object is capable of receiving messages  processing data  and sending messages to other objects   For a language to be object-oriented in may include features as encapsulation  modularity  polymorphism  and inheritance  but it is not a requirement  Object-oriented programming languages that make use of classes are often referred to as classed-based programming languages  but it is by no means a must to make use of classes to be object-oriented   JavaScript uses prototypes to define object properties  including methods and inheritance   Conclusion  JavaScript IS object-oriented

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IMO  and it is only an opinion  the key characteristic of an object orientated language would be that it would support polymorphism   Pretty much all dynamic languages do that   The next characteristic would be encapsulation and that is pretty easy to do in Javascript also   However in the minds of many it is inheritance  specifically implementation inheritance  which would tip the balance as to whether a language qualifies to be called object oriented   Javascript does provide a fairly easy means to inherit implementation via prototyping but this is at the expense of encapsulation   So if your criteria for object orientation is the classic threesome of polymorphism  encapsulation and inheritance then Javascript doesn t pass   Edit  The supplementary question is raised  how does prototypal inheritance sacrifice encapsulation   Consider this example of a non-prototypal approach -  function MyClass         var  value   1      this getValue   function     return  value        The  value attribute is encapsulated  it cannot be modified directly by external code   We might add a mutator to the class to modify it in a way entirely controlled by code that is part of the class   Now consider a prototypal approach to the same class -  function MyClass       var  value   1    MyClass prototype getValue   function     return  value      Well this is broken   Since the function assigned to getValue is no longer in scope with  value it can t access it   We would need to promote  value to an attribute of this but that would make it accessable outside of the control of code written for the class  hence encapsulation is broken   Despite this my vote still remains that Javascript is object oriented   Why   Because given an OOD I can implement it in Javascript

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Hanselminutes episode 146 looks at OO Ajax  It was a good show and definitely a good show to help form an opinion

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I think when you can follow the same or similar design patterns as a true OO language like Java C   you can pretty much call it an OO language  Some aspects are obviously different but you can still use very well established OO design pattersn

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JavaScript is Object-Based  not Object-Oriented  The difference is that Object-Based languages don t support proper inheritance  whereas Object-Oriented ones do   There is a way to achieve  normal  inheritance in JavaScript  Reference here   but the basic model is based on prototyping

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Objects in JavaScript inherit directly from objects  What can be more object oriented

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For me personally the main attraction of OOP programming is the ability to have self-contained classes with unexposed  private  inner workings    What confuses me to no end in Javascript is that you can t even use function names  because  you run the risk of having that same function name somewhere else in any of the external libraries that you re using   Even though some very smart people have found workarounds for this  isn t it weird that Javascript in its purest form requires you to create code that is highly unreadable   The beauty of OOP is that you can spend your time thinking about your app s logic  without having to worry about syntax

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Javascript is a multi-paradigm language that supports procedural  object-oriented  prototype-based  and functional programming styles   Here is an article discussing how to do OO in Javascript

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Misko Hevery did an excellent introductory Google Tech Talk where he talks about objects in Javascript  I ve found this to be a good starting point for people either questioning the use of objects in Javascript  or wanting to get started with them    Introduction to JavaScript and Browser DOM

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I would say it has capabilities to seem OO  Especially if you take advantage of it s ability to create methods on an existing object  anonymous methods in some languages   Client script libraries like jquery  jquery com  or prototype  prototypejs org  are good examples of libraries taking advantage of this  making javascript behave pretty OO-like

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Yes and no   JavaScript is  as Douglas Crockford puts it   the world s most misunderstood programming language   He has some great articles on JavaScript that I d strongly recommend reading on what exactly JavaScript is  It has more in common with LISP that C

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I am responding this question bounced from another angle   This is an eternal topic  and we could open a flame war in a lot of forums   When people assert that JavaScript is an OO programming language because they can use OOD with this  then I ask  Why is not C an OO programming language  Repeat  you can use OOD with C and if you said that C is an OO programming language everybody will said you that you are crazy   We could put here a lot of references about this topic in very old books and forums  because this topic is older than the Internet     JavaScript has not changed for many years  but new programmers want to show JavaScript is an OO programming language  Why  JavaScript is a powerful language  but is not an OO programming language   An OO programming language must have objects  method  property  classes  encapsulation  aggregation  inheritance and polymorphism  You could implement all this points  but JavaScript has not them   An very illustrate example  In chapter 6 of  Object-Oriented JavaScript  describe 10 manners to implement  inheritance   How many manners there are in Java  One  and in C    One  and in Delphi  Object Pascal   One  and in Objective-C  One   Why is this different  Because Java  C    Delphi and Objective-C are designed with OOP in mind  but not JavaScript   When I was a student  in 1993   in university  there was a typical home work  Implement a program designed using a OOD  Object-oriented design  with a non-OO language  In those times  the language selected was C  not C     The objective of this practices was to make clear the difference between OOD and OOP  and could differentiate between OOP and non-OOP languages   Anyway  it is evidence that not all people have some opinion about this topic     Anyway  in my opinion  JavaScript is a powerful language and the future in the client side layer

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I think a lot of people answer this question  no  because JavaScript does not implement classes  in the traditional OO sense  Unfortunately  IMHO   that is coming in ECMAScript 4  Until then  viva la prototype   -

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Objects in JavaScript inherit directly from objects  What can be more object oriented

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It is object oriented  but not based on classes  it s based on prototypes

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Languages do not need to behave exactly like Java to be object-oriented   Everything in Javascript is an object  compare to C   or earlier Java  which are widely considered object-oriented to some degree but still based on primitives   Polymorphism is a non-issue in Javascript  as it doesn t much care about types at all   The only core OO feature not directly supported by the syntax is inheritance  but that can easily be implemented however the programmer wants using prototypes  here is one such example

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Technically it is a prototype language  but it s easy to to OO in it

[javascript] Is JavaScript object-oriented?

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