JavaScript 揭示模块模式公共变量未更新

Question

我正在使用带有显示模块模式的 Angular 服务。该服务在内部从 Web 服务中提取字符串资源，并通过“字符串”公共变量使它们可用。我必须初始化私有的“字符串”变量，因为它是在进行服务调用之前被引用的。

我从服务中获取正确的字符串数据并将其复制到私有“字符串”变量中。但是，当客户端引用公共“字符串”时，它仍然保留其原始值。

知道我做错了什么，或者如何让公共“字符串”更新？

'use strict';

io1App.factory('Resources', ['$rootScope', 'DataService', '$q',
function ($rootScope, DataService, $q) {

   var urlBase = '/api/sfc/resource';

    // Need to pre-define 'ERROR_HEADER', since it is referenced in Index.html...before we have a chance to download it from the server.
   var strings = {
       'ERROR_HEADER': 'Error!'
   };

    var getStringResources = function (locale) {

        var url = urlBase + '/' + locale;

        var deferred = $q.defer();

        var promise = DataService.GetMethod(url);

        // Note that DataService.GetMethod(...) is returning a $q promise
        promise.then(function (data) {
            strings = data;
            deferred.resolve();
        },
        function (err) {
            deferred.reject(err);
        });

        return deferred.promise;
    };

    return {
        Strings: strings,
        GetStringResources: getStringResources
    }
}]);

服务调用将返回的数据设置为私有“字符串”变量

promise.then(function (data) {
            strings = data;
            deferred.resolve();
        },

私有“字符串”现在显示以下内容（通过 Chrome 开发者工具）：

strings = {
       'ERROR_HEADER': 'Error!'
       'INVALID_PROCESS_ORDER': 'Process Order [%d] could not be entered because it does not belong to Manfacturing Order [%d]',
       'DUPLICATE_PROCESS_ORDER': 'Process Order [%d] already entered.',
       'USER_NOT_ITAR': 'Manufacturing order [%d] is ITAR, and you are not ITAR approved.  You cannot proceed with this order.  Please contact your supervisor.'
   };

然而，当在 Angular 控制器中引用公共“字符串”时，“字符串”仍在引用私有“字符串”的原始值。

Resource.Strings：

{
   'ERROR_HEADER': 'Error!'
};

有什么建议吗？

Answer 1

您将用data 完全替换strings 变量。它们是不同的对象并且具有不同的引用，因此任何引用了之前的strings 对象的客户端代码都不会看到更改。

您可以扩充现有的 strings 对象，而不是替换。

promise.then(function (data) {
    // Merge properties into `strings`
    // You could also use any other "extension" technique, e.g. _.extend()
    for (var k in data) {
        if (data.hasOwnProperty(k)) {
            strings[k] = data[k];
        }
    }
    deferred.resolve();
},

Answer 2

您从工厂方法返回的 JavaScript 对象永远不会使用新的字符串对象进行更新。您需要保留对它的引用才能更新“公共视图”：

service = {
    Strings: strings,
    GetStringResources: getStringResources
};
return service;

然后更新您的 .then 回调以更新私有变量和公共服务对象：

.then(function(data) {
    strings = service.strings = data;
    deferred.resolve(data); // don't need to resolve this with the strings, but why not?
}, function error(){...});

但是，由于您不再真正拥有“私有数据”（只有对公开变量的私有引用），因此您根本不需要私有字符串变量：

io1App.factory('Resources', ['$rootScope', 'DataService', '$q',
function ($rootScope, DataService, $q) {

    var urlBase = '/api/sfc/resource';

    var service = {
        // Need to pre-define 'ERROR_HEADER', since it is referenced in Index.html...before we have a chance to download it from the server.
        Strings: { 'ERROR_HEADER': 'Error!' },
        GetStringResources: function (locale) {
            var url = urlBase + '/' + locale;
            var deferred = $q.defer();
            var promise = DataService.GetMethod(url);

            // Note that DataService.GetMethod(...) is returning a $q promise
            promise.then(function (data) {
                service.strings = data;
                deferred.resolve(data); // don't need to resolve this with the strings, but why not?
            },
        function (err) {
            deferred.reject(err);
        });

        return deferred.promise;
    };
    return service;
}]);