javascript - Angular's NgClick has outdated scope -

i'm experiencing strange behaviour, don't know who's fault is.

i have 3 variables in $scope can changed user. bind select object through ng-model.

<select ng-options="hour.label hour in hours track hour.val" ng-model="new_hour"></select> hh : <select ng-options="minute.label minute in minutes track minute.val" ng-model="new_minute"></select> mm :  <br />  new_hour = {{ new_hour }}<br /> new_minute = {{ new_minute }} </br> 

where variables initialized follows:

$scope.minutes = [];  for(var = 0; < 60; ++i) {     var min = string(i);     if(i < 10)     min = "0" + min;      $scope.minutes.push({ val: i, label: min}); }  $scope.hours = $scope.minutes.slice(0, 24);  $scope.new_minute = $scope.minutes[0]; $scope.new_hour = $scope.hours[0]; 

whenever choose different time, values of $scope.new_hour , $scope.new_minute change expected.

however, have button has ngclick , calls function in $scope.

<button ng-click="add_value()">add value</button> 

if select new (minute) value , click on button, $scope function sees old values , not new ones:

$scope.add_value = function() {     console.log("new_minute: " + $scope.new_minute.val); } 

let's i've chosen 03 , click on button. console shows new_minute: 0.

however, if modify code:

<button ng-click="add_value(new_minute.val)">add vaue</button> 

and

$scope.add_value = function(new_minute) {     console.log("new_minute: " + new_minute); } 

then value passed add_value correct. if open inspect console , inspect value of $scope.new_minute.val, $scope.new_minute.val differs local variable new_minute.

i've prepared fiddle basic structure of code: https://jsfiddle.net/shaoran/tnvou6ud/1/

there works expected, cannot reproduce behaviour. has idea might going on?