标签上的Angular.js ng-click事件会触发两次

给出以下使用angular.js的代码

Plunkr:http://plnkr.co/edit/i4MAzs

HTML:

  Try clicking on the labels. 

  
    Value1: 
   

  
    Value2: 
   

  value1 = {{value1}}

  value2 = {{value2}}

  fire_count = {{fire_count}}

使用Javascript:

angular.module('App', []);

function Ctrl($scope) {
  $scope.value1 = true;
  $scope.value2 = 'YES'
  $scope.fire_count = 0;

  $scope.toggleValue1 = function(){
    $scope.value1 = !$scope.value1;
    $scope.fire_count++;
    console.log("Clicked!");
  }

  $scope.toggleValue2 = function(){
    $scope.value2 = !$scope.value2;
    $scope.fire_count++;
    console.log("Clicked!");
  }
}

单击"Value2"标签时,单击事件将触发两次.仅当ng-click附加到标签时才会发生这种情况.当它附加到输入元素时,一切都按预期工作.

有人可以解释发生了什么吗？