json - How to get objectId from Parse.com rest api in javascript -

i working on project using parse.com rest api , ionic/angularjs.

when issue post request, objectid response body.

i can see objectid included in response in json format, can´t seem extract it.

var signup = new signup(signupdata);  var response = signup.$save(); // using angularjs $resource console.log(response); 

when log reponse in console: object { $$state: object } "dotting" $$state returns number.

any appreciated.

i never used parse.com if using $resource code below should works

var signup = new signup(signupdata);  signup.$save(function(response){  console.log(response); });