javascript - 为什么 Angular 绑定(bind)不适用于服务原语

Question

我有一个例子Plunker 。为什么绑定(bind)到 count: 0 不起作用？以下是 *.js 文件中的代码:

var app = angular.module("MyApp", []);

app.controller("objectCtrl", function($scope, sharingData) {   $scope.message = sharingData.message; });

app.controller("primitiveCtrl", function($scope, sharingData) {   $scope.count = sharingData.message.count; });

app.controller("watchCtrl", function($scope, sharingData) {   $scope.message = {};

  $scope.$watch(function() {
    return sharingData.message.count;   }, function(value) {
    $scope.message.count = value;   }); });

app.factory('sharingData', function() {   return {
    count: 0,
    message: {
      count: 0
    }   }; });

app.run(function($rootScope, sharingData) {   $rootScope.Inc = function() {
    sharingData.message.count = ++sharingData.count;   }; });

Answer 1

因为变量不是通过引用传递的，而是通过值传递的。

为了实现这一目标，您必须这样做:

app.controller("primitiveCtrl", function($scope, sharingData) {   
    $scope.count = sharingData.message;
});

还有:

  count from primitiveCtrl:   {{count.count}}

http://plnkr.co/edit/h8A8PwGJuhD2imRbEsNM?p=preview

编辑:事实是不可能在 JavaScript 中通过引用传递原始值。可能与此类似的一件事如下:

app.controller("primitiveCtrl", function($scope, sharingData) {   
    $scope.getValue= function(){
      return sharingData.message.count;

    };
});

还有:

  count from primitiveCtrl:   {{getValue()}}

http://plnkr.co/edit/h8A8PwGJuhD2imRbEsNM?p=preview