dependency injection - AngularJS: Service vs provider vs factory -

what differences between service, provider , factory in angularjs?

from angularjs mailing list got an amazing thread explains service vs factory vs provider , injection usage. compiling answers:

services

syntax: module.service( 'servicename', function );
result: when declaring servicename injectable argument you provided instance of function. in other words new functionyoupassedtoservice().

factories

syntax: module.factory( 'factoryname', function );
result: when declaring factoryname injectable argument provided the value returned invoking function reference passed module.factory.

providers

syntax: module.provider( 'providername', function );
result: when declaring providername injectable argument you provided with (new providerfunction()).$get(). constructor function instantiated before $get method called - providerfunction function reference passed module.provider.

providers have advantage can configured during module configuration phase.

see here provided code.

here's great further explanation misko:

provide.value('a', 123);  function controller(a) {   expect(a).toequal(123); } 

in case injector returns value is. if want compute value? use factory

provide.factory('b', function(a) {   return a*2; });  function controller(b) {   expect(b).toequal(246); } 

so factory function responsible creating value. notice factory function can ask other dependencies.

but if want more oo , have class called greeter?

function greeter(a) {   this.greet = function() {     return 'hello ' + a;   } } 

then instantiate have write

provide.factory('greeter', function(a) {   return new greeter(a); }); 

then ask 'greeter' in controller this

function controller(greeter) {   expect(greeter instanceof greeter).tobe(true);   expect(greeter.greet()).toequal('hello 123'); } 

but way wordy. shorter way write provider.service('greeter', greeter);

but if wanted configure greeter class before injection? write

provide.provider('greeter2', function() {   var salutation = 'hello';   this.setsalutation = function(s) {     salutation = s;   }    function greeter(a) {     this.greet = function() {       return salutation + ' ' + a;     }   }    this.$get = function(a) {     return new greeter(a);   }; }); 

then can this:

angular.module('abc', []).config(function(greeter2provider) {   greeter2provider.setsalutation('halo'); });  function controller(greeter2) {   expect(greeter2.greet()).toequal('halo 123'); } 

as side note, service, factory, , value derived provider.

provider.service = function(name, class) {   provider.provide(name, function() {     this.$get = function($injector) {       return $injector.instantiate(class);     };   }); }  provider.factory = function(name, factory) {   provider.provide(name, function() {     this.$get = function($injector) {       return $injector.invoke(factory);     };   }); }  provider.value = function(name, value) {   provider.factory(name, function() {     return value;   }); };