AngularJS Factory and Service

Question

EDIT Jan 2016  Since this still gets attention  Since asking this I ve completed a few AngularJS projects  and for those I mostly used factory  built up an object and returned the object at the end  My statements below are still true  however   EDIT   I think I finally understand the main difference between the two  and I have a code example to demonstrate  I also think this question is different to the proposed duplicate  The duplicate says that service is not instantiable  but if you set it up as I demonstrated below  it actually is  A service can be set up to be exactly the same as a factory  I will also provide code that shows where factory fails over service  which no other answer seems to do   If I set up VaderService like so  ie as a service    var module   angular module  MyApp services         module service  VaderService   function         this speak   function  name            return  Join the dark side     name              Then in my controller I can do this   module controller  StarWarsController   function  scope  VaderService         scope luke   VaderService speak  luke             With service  the VaderService injected in to the controller is instantiated  so I can just call VaderService speak  however  if I change the VaderService to module factory  the code in the controller will no longer work  and this is the main difference  With factory  the VaderService injected in to the controller is not instantiated  which is why you need to return an object when setting up a factory  see my example in the question    However  you can set up a service in the exact same way as you can set up a factory  IE have it return an object  and the service behaves the exact same as a factory  Given this information  I see no reason to use factory over service  service can do everything factory can and more   Original question below     I know this has been asked loads of times  but I really cannot see any functional difference between factories and services  I had read this tutorial  http   blogs clevertech biz startupblog angularjs-factory-service-provider  And it seems to give a reasonably good explanation  however  I set up my app as follows   index html   lt  DOCTYPE html gt   lt html gt       lt head gt       lt title gt My App lt  title gt       lt script src  lib angular angular js  gt  lt  script gt       lt script type  text javascript  src  js controllers js  gt  lt  script gt       lt script type  text javascript  src  js VaderService js  gt  lt  script gt       lt script type  text javascript  src  js app js  gt  lt  script gt       lt  head gt        lt body ng-app  MyApp  gt            lt table ng-controller  StarWarsController  gt               lt tbody gt               lt tr gt  lt td gt   luke   lt  td gt  lt  tr gt               lt  tbody gt           lt  table gt       lt  body gt   lt  html gt    app js   angular module  MyApp        MyApp services      MyApp controllers        controllers js   var module   angular module  MyApp controllers         module controller  StarWarsController   function  scope  VaderService        var luke   new VaderService  luke         scope luke   luke speak          VaderService js  var module   angular module  MyApp services         module factory  VaderService   function         var VaderClass   function padawan            this name   padawan          this speak   function                  return  Join the dark side     this name                       return VaderClass        Then when I load up index html I see  Join the dark side luke   great  Exactly as expected  However if I change VaderService js to this  note module service instead of module factory    var module   angular module  MyApp services         module service  VaderService   function         var VaderClass   function padawan            this name   padawan          this speak   function                  return  Join the dark side     this name                       return VaderClass        Then reload index html  I made sure I emptied the cache and did a hard reload   It works exactly the same as it did with module factory  So what is the real functional difference between the two

User · Accepted Answer

Service vs Factory       The difference between factory and service is just like the difference between a function and an object  Factory Provider   Gives us the function s return value ie  You just create an object  add properties to it  then return that same object When you pass this service into your controller  those properties on the object will now be available in that controller through your factory   Hypothetical Scenario  Singleton and will only be created once  Reusable components Factory are a great way for communicating between controllers like sharing data  Can use other dependencies Usually used when the service instance requires complex creation logic Cannot be injected in  config   function   Used for non configurable services If you re using an object  you could use the factory provider    Syntax  module factory  factoryName   function     Service Provider   Gives us the instance of a function  object - You just  instantiated with the    new    keyword and you   ll add properties to    this    and the service will return    this    When you pass the service into your controller  those properties on    this    will now be available on that controller through your service   Hypothetical Scenario  Singleton and will only be created once  Reusable components Services are used for communication between controllers to share data You can add properties and functions to a service object by using the  this keyword Dependencies are injected as constructor arguments Used for simple creation logic Cannot be injected in  config   function   If you re using a class you could use the service provider Syntax  module service    serviceName     function     Sample Demo   In below example I have define MyService and MyFactory  Note how in  service I have created the service methods using this methodname  In  factory I have created a factory object and assigned the methods to it   AngularJS  service    module service  MyService   function          this method1   function                     method1 logic                this method2   function                     method2 logic                 AngularJS  factory    module factory  MyFactory   function          var factory             factory method1   function                     method1 logic                factory method2   function                     method2 logic                return factory          Also Take a look at this beautiful stuffs  Confused about service vs factory  AngularJS Factory  Service and Provider  Angular js  service vs provider vs factory

User · Answer

Factory and Service is a just wrapper of a provider    Factory  Factory can return anything which can be a class constructor function   instance of class  string  number or boolean  If you return a constructor function  you can instantiate in your controller    myApp factory  myFactory   function            any logic here         Return any thing  Here it is object   return       name   Joe          Service  Service does not need to return anything  But you have to assign everything in this variable  Because service will create instance by default and use that as a base object   myApp service  myService   function            any logic here      this name    Joe       Actual angularjs code behind the service   function service name  constructor        return factory name     injector   function  injector            return  injector instantiate constructor                It just a wrapper around the factory  If you return something from service  then it will behave like Factory   IMPORTANT  The return result from Factory and Service will be cache and same will be returned for all controllers   When should i use them   Factory is mostly preferable in all cases  It can be used when you have constructor function which needs to be instantiated in different controllers   Service is a kind of Singleton Object  The Object return from Service will be same for all controller  It can be used when you want to have single object for entire application  Eg  Authenticated user details   For further understanding  read   http   iffycan blogspot in 2013 05 angular-service-or-factory html  http   viralpatel net blogs angularjs-service-factory-tutorial

User · Answer

If you use a service you will get the instance of a function   this  keyword    If you use a factory you will get the value that is returned by invoking the function reference  the return statement in factory    Factory and Service are the most commonly used recipes  The only difference between them is that Service recipe works better for objects of custom type  while Factory can produce JavaScript primitives and functions   Reference

User · Answer

provide service  They are technically the same thing  it s actually a different notation of using the provider function of the  provide service     If you re using a class  you could use the service notation  If you re using an object  you could use the factory notation    The only difference between the service and the factory notation is that the service is new-ed and the factory is not  But for everything else they both look  smell and behave the same  Again  it s just a shorthand for the  provide provider function      Factory  angular module  myApp   factory  myFactory   function        var  myPrivateValue   123     return       privateValue  function     return  myPrivateValue                  Service  function MyService       this  myPrivateValue   123     MyService prototype privateValue   function       return this  myPrivateValue      angular module  myApp   service  MyService   MyService

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