Difference between Service, Factory and Provider in AngularJS

gistfile1.js

// Source: https://groups.google.com/forum/#!topic/angular/hVrkvaHGOfc
// jsFiddle: http://jsfiddle.net/pkozlowski_opensource/PxdSP/14/
// author: Pawel Kozlowski

var myApp = angular.module('myApp', []);

//service style, probably the simplest one
myApp.service('helloWorldFromService', function() {
    this.sayHello = function() {
        return "Hello, World!"
    };
});

//factory style, more involved but more sophisticated
myApp.factory('helloWorldFromFactory', function() {
    return {
        sayHello: function() {
            return "Hello, World!"
        }
    };
});
    
//provider style, full blown, configurable version     
myApp.provider('helloWorld', function() {
    // In the provider function, you cannot inject any
    // service or factory. This can only be done at the
    // "$get" method.

    this.name = 'Default';

    this.$get = function() {
        var name = this.name;
        return {
            sayHello: function() {
                return "Hello, " + name + "!"
            }
        }
    };

    this.setName = function(name) {
        this.name = name;
    };
});

//hey, we can configure a provider!            
myApp.config(function(helloWorldProvider){
    helloWorldProvider.setName('World');
});
        

function MyCtrl($scope, helloWorld, helloWorldFromFactory, helloWorldFromService) {
    
    $scope.hellos = [
        helloWorld.sayHello(),
        helloWorldFromFactory.sayHello(),
        helloWorldFromService.sayHello()];
}​

1. When you register the Service you return an object, when Angular needs to inject "service" into any component, it will inject this object.
2. When you register the Factory, you return a constructor function. When angular needs to inject "service" into any component, it will first do a

new factoryReturnedFunction();

and then inject it. This will be done only for the first time service is requested. For all subsequent injections, object created first time will be used.
3. When you register a Provider, it has same behavior as Factory above. The function assigned to ...$get..., will be used as constructor function.

thanks for sharing, you help me alot to understand.

Nice Info

@Mithrandir0x, thank you for the example!
If we need a service and we define it using the "factory" method, is it write or false?

https://github.com/SAM-BI/jira-rest-angular

Thanks, this is very helpful. :)

Thanks much for the explanation. would you tell me, where to use which, I mean, how to make a right choice among them?
Appreciate your time

Thanks for the helpful example.

very thanks

Many Thanks !

Nice explanation about Service / Provider / Factory, Very useful, Thank you very much !

Nice Explanation. Helpful