Jquery 在knockoutjs“；未捕获错误：无法分析绑定；错误，但代码可以工作

我正在使用knockout js映射，在尝试执行示例时，我遇到了控制台错误

未捕获错误：无法分析绑定。消息：ReferenceError: loadUserData未定义；绑定值：单击：loadUserData

这里是代码

<form action="#" method="post">
    <p>First name: <input data-bind='value: firstName' /></p>
    <p>Last name: <input data-bind='value: lastName' /></p>
    <div>
        Your favorite food:
        <select data-bind='options: activities, value: favoriteHobby'></select>
    </div>
    <p><button data-bind='click: loadUserData'>Load data</button></p>
    <p><button data-bind='click: saveUserData'>Save Data</button></p>
</form>
<script>
    function PersonViewModel() {
        var self = this;
        self.firstName = "";
        self.lastName = "";
        self.activities = [];
        self.favoriteHobby = "";
        self.loadUserData = function () {
            $.getJSON("/get-user-data.json", function (data) {
                var viewModel = ko.mapping.fromJS(data);
                ko.applyBindings(viewModel);
            });
        }
        self.saveUserData = function () {
            var data_to_send = { userData: ko.toJSON(self) };
            $.post("/save-user-data", data_to_send, function (data) {
                alert("Your data has been posted to the server!");
            }).fail(function () {
                alert("Ensure the Url before save the data");
            });
        }
    }
    ko.applyBindings(new PersonViewModel());
</script>

---

单击“加载数据”按钮时，会出现错误，但示例有效，如何清除此错误。

正如@user3297291所指出的，您不能调用ko.applyBindings两次。取而代之的是，使视图模型的属性可以被观察到，当它们发生变化时，knockout将自动更新您的UI：

function PersonViewModel() {
    var self = this;
    self.firstName = ko.observable();
    self.lastName = ko.observable();
    self.activities = ko.observableArray();
    self.favoriteHobby = ko.observable();
    self.loadUserData = function () {
        return $.getJSON("/get-user-data.json", function (result) {
            self.firstName(result.firstName)
                .lastName(result.lastName)
                .favoriteHobby(result.favoriteHobby)
                .activites(result.activities);
        });
    }
}
ko.applyBindings(new PersonViewModel());

---

在knockout中，您可以通过使用可观察项来更新UI。您不能像在

loadUserData

的回调中那样应用绑定两次。我建议阅读教程，了解如何使用服务器上的数据更新viewmodel。

function PersonViewModel() {
    var self = this;
    self.firstName = ko.observable();
    self.lastName = ko.observable();
    self.activities = ko.observableArray();
    self.favoriteHobby = ko.observable();
    self.loadUserData = function () {
        return $.getJSON("/get-user-data.json", function (result) {
            self.firstName(result.firstName)
                .lastName(result.lastName)
                .favoriteHobby(result.favoriteHobby)
                .activites(result.activities);
        });
    }
}
ko.applyBindings(new PersonViewModel());