AngularJS 验证码60秒倒计时功能的实现

<a href="javascript:" rel="external nofollow" ng-click="sendphonecode(reg_phone)" ng-class="paraclass" ng-bind="paracont">获取验证码</a> 

angular.module('controllers', []).controller('registerCtrl', function($scope,$interval){ 
    $scope.paracont = "获取验证码"; 
    $scope.paraclass = "but_null"; 
    $scope.paraevent = true; 
    var second = 60, 
      timePromise = undefined; 
    timePromise = $interval(function(){ 
     if(second<=0){ 
      $interval.cancel(timePromise); 
      timePromise = undefined; 
      second = 60; 
      $scope.paracont = "重发验证码"; 
      $scope.paraclass = "but_null"; 
      $scope.paraevent = true; 
     }else{ 
      $scope.paracont = second + "秒后可重发"; 
      $scope.paraclass = "not but_null"; 
      second--; 
     } 
    },1000,100); 
});