javascript - 未捕获的TypeError:无法读取未定义的属性'fromJSON'

我试图在ajax调用从以下页面返回后显示菜单数据：

<head>
    <link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0-alpha.6/css/bootstrap.min.css">

    <script type='text/javascript' src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.1/knockout-min.js"></script>
    <script type='text/javascript' src='https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.min.js'></script>
    <!-- <script type='text/javascript' src='https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0-alpha.6/js/bootstrap.min.js'></script>
    <script type='text/javascript' src='https://cdnjs.cloudflare.com/ajax/libs/tether/1.4.0/js/tether.js'></script> -->
</head>


<body>

    <h1>page loaded</h1>

    <div data-bind="foreach: menu">
        <!-- ko foreach: items -->
            <span data-bind="$data.name"></span>
        <!-- /ko -->
    </div>
</body>




<script>

    function OrderPageViewModel() {
        var self = this;

        // self.menu_loaded_success_callback = function(data) {
        //         var retrieved_menu = data["menu"];
        //         self.menu = ko.observable(retrieved_menu);
        //         console.log(retrieved_menu)
        //         alert(data);
        //     }
        //
        // self.get_data(menu_url).done(self.menu_loaded_success_callback);

    }

    var menu_url = "menu/get-menu";

    get_menu_data = function(url_ending){
        console.log("running get_data");
        var URL = "/api/&/".replace("&", url_ending);
        console.log("URL: ", URL);
        return $.ajax({
            dataType: "json",
            url: URL,
            // type: "GET",
        });
    }

    get_menu_data(menu_url).done(function(data){
        var vm = new OrderPageViewModel();
        console.log(data);
        vm = ko.mapping.fromJSON(data);
        ko.applyBindings(vm);
    }).fail(function(){
        alert("failed");
    });

    // ko.applyBindings(new OrderPageViewModel());

</script>

javascript - 未捕获的TypeError:无法读取未定义的属性'fromJSON'-LMLPHP

我按照wait for ajax result to bind knockout model的示例进行操作，它说的是Uncaught TypeError: Cannot read property 'fromJSON' of undefined

最佳答案

fromJSON方法是Knockout mapping plugin的一部分，它没有包含在代码Knockout库中。

您必须单独包含映射插件，因此在添加了剔除后添加以下行：

<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout.mapping/2.4.1/knockout.mapping.min.js" type='text/javascript'></script>

fromJson

javascript - 未捕获的TypeError:无法读取未定义的属性'fromJSON'