app.js

  $scope.weighItem = function() {

    return $http({
      method: 'GET',
      url: 'https://jsonp.afeld.me/?url=http://smartshop-sjroot.rhcloud.com/api/readings'
    });
  }

  $scope.updateReading = function() {
    $scope.weighItem().then(function success(res) {
      console.log(res);
      $scope.newItem.value = res.data.value;
      $scope.newItem.unit = res.data.unit;
    }, function error(res){
      console.log(res);
    });

  }