angular_ajax_json_samp.js

var controller = function($http){

    var json_args = {
        num1: 5,
        num2: 3
    };

    var showResult = function(res){
        alert(res.data.sum);
    }

      var req = {
          url: "/addnums",
          method: "post",
          headers: {
              "Content-type": "application/json"
          },
          data: json_args
      };

    var promise = $http(req);
    promise.then(showResult);
};