javascript - $watchCollection 和多个表达式不起作用

Question

我有两个数组，每个数组都有 bool 值，我尝试使用 $watchCollecion 函数在其中一个数组发生某些更改时显示一条消息，但由于某种原因它不起作用。

我想看看这个 example 有什么问题

Controller

  $scope.arrayCategoryA = [];
  $scope.arrayCategoryB = [];

  $scope.$watchCollection(['arrayCategoryA', 'arrayCategoryB'], function(newVal, oldVal, scope){
    console.log("something changed");
  }, true);

  $http.get("categoryA.json").success(function(data) {
     $scope.categoryA = data;
     for (var i = 0; i < $scope.categoryA.length; i++) 
     $scope.arrayCategoryA[i] = true;
  });

  $http.get("categoryB.json").success(function(data) {
     $scope.categoryB = data;
     for (var j = 0; j < $scope.categoryB.length; j++) 
     $scope.arrayCategoryB[j] = true;
  });

Answer 1

AngularJS has always had a Scope.$watch() function as means to observe [and react to] changes in a given value. With AngularJS 1.1.4, however, they added the Scope.$watchCollection() function as a means to observe changes in a collection (either as an Array or an Object).

$watchCollection 仅适用于一个数组或对象。因此您必须将代码更改为单一监视。

$scope.$watchCollection('arrayCategoryA', function(newVal, oldVal){
    console.log("something changed 1");
}, true);
$scope.$watchCollection('arrayCategoryB', function(newVal, oldVal){
    console.log("something changed 2");
}, true);