将Knockout observableArray JSON保存到localStorage

Question

我正在尝试使用ko.toJSON方法将observableArray保存到localStorage.在第一页加载时,我的应用程序将从服务器接收JSON对象并填充observableArray.我想将它存储在localStorage中以进行优化和离线使用,但是ko.toJSON正在返回[],即使其中有明显的数据.

我能够在这个jsFiddle上重现这个问题

HTML

<span data-bind="text: locations().length"></span>
<div data-bind="foreach: locations">
    <div>
        <span data-bind="text: title"></span>
        <span> </span>
        <span data-bind="text: timeZone"></span>
    </div>
</div>
<pre data-bind="text: output"></pre>

JavaScript的

var dataFromServer = [
    {name: "Cleveland", zone: "EST"},
    {name: "Chicago", zone: "CST"},
    {name: "New York", zone: "EST"}
];

var MyNS = window.MyNS || {};
MyNS.ViewModel = function () {
    var self = this;
    self.locations = ko.observableArray([]);
    self.load = function (){
        var mappedData = ko.utils.arrayMap(dataFromServer, function(item) {
            return new MyNS.Location(item.name, item.zone);
        });
        self.locations(mappedData);
    };
    self.output = ko.toJSON(self.locations());
    self.execute = function(){
        self.load();
        ko.applyBindings(self);
    };
};
MyNS.Location = function (t, z) {
    this.title = t;
    this.timeZone = z;
};
var model = new MyNS.ViewModel();
model.execute();

Answer 1

问题在于，output当位置数组为空时，该变量的值仅在第一次运行构造函数时写入一次。要更新位置更改时的输出，您可以将其转换为计算的可观察量，如下所示：

self.output = ko.computed(function(){
    return ko.toJSON(self.locations())
});

更新的小提琴：http://jsfiddle.net/wvgRL/4/