I want to to set checkbox status in state parameter in angular js?

I am implementing checkbox and also I want to set status(true, false) in url as a parameter But only false value is set in url parameter. But When I click on checkbox then true value is not set in url as a parameter. I am using $location.search. I not able to find out what is the issue with true value.

var app = angular.module('demo', ['rzModule', 'ui.bootstrap']);
app.controller('MainCtrl', function($scope, $rootScope, $timeout) {    
  $scope.confirm = function(){
  alert($scope.checkboxModel.value);
  $location.search({checkbox: $scope.checkboxModel.value});           
}          
})

<link href="http://ift.tt/1FHelXo" rel="stylesheet"/>
   
<script src="http://ift.tt/1MeTcXW"></script>
<script src="http://ift.tt/2vbLpZF"></script>
<script src="http://ift.tt/2rcl0tm"></script>
   
<div ng-app="demo">
  <div ng-controller="MainCtrl" class="wrapper">
  checkbox status should set in url as parameter
    <label>
              <input type="checkbox" ng-model="checkboxModel.value" data-ng-change="confirm()"/>
            </label>
  </div>
</div>