angularjs - Can't redefine service defined as constant -

here temp.js

angular.module('temp', [])     .service('tempfactory', function() {         this.a =10;     }); 

and here temp.spec.js

describe('temp', function() {     var tempfactory;      beforeeach(function() {         var mockedtempfactory = {};          module('temp', function($provide) {             $provide.value('tempfactory', mockedtempfactory);         });          mockedtempfactory.a = 20;          inject(function(_tempfactory_) {             tempfactory = _tempfactory_;         });     });  it('console.log of property', function() {     console.log(tempfactory.a); }); 

});

in console value of 20.

but if define tempfactory this:

angular.module('temp', [])     .constant('tempfactory', {         a: 10;     }); 

in console value of 10.

why can't redefine tempfactory defined constant, can redefine tempfactory defined service, value or factory?

because when create service, provide constructor function it

.service('tempfactory', function() {     this.a = 10; }) 

angular creates instance of function kinda this:

var tempfactoryinstance = new tempfactory(); return tempfactoryinstance; 

and returns instance, access a property right away.

but constant not anything, returnes you've passed it, so

.constant('tempfactory', function() {     this.a = 10; }) 

will return function you. if want able access property a in situation, have "instantiate" it:

var instance = new tempfactory(); console.log(instance.a); // 10 

see plunker.

you can read more behavior of different provider in documentation.