AngularJS - Simple Directive Use

HTML

<link rel="stylesheet" href="http://twitter.github.com/bootstrap/assets/css/bootstrap.css">
<script src="http://code.angularjs.org/1.0.0/angular-1.0.0.js"></script>
<div ng-app="myApp">
    <div ng-controller="Ctrl">
        <label>Checkbox:
            <input type="checkbox" id="check1" ng-model="active" ng-change="check('check1')">
        </label>
    </div>
</div>

CSS

.ui-state-highlight { background-color: #EEEEEE; }

JavaScript

var app = angular.module('myApp', []);
app.controller('Ctrl',function($scope){
    $scope.active = true;
    $scope.check = function(clickedid) { 
    alert('click');
      if (document.getElementById(clickedid).checked === true) {
        return false;
      } else {
       var box= confirm("Are you sure you want to do this?");
        if (box===true){    // yes sure
            return true;
        }
        else{      // cancel
           document.getElementById(clickedid).checked = true;
        }
      }
    };

});