javascript - knockout 计数器错误 (ASP.NET MVC)

Question

我有通过 Knockout JS 编写的脚本。

这里是查看代码

 <span data-bind='text: numberOfClicks'>&nbsp;</span>/<span data-bind='text: totalnumberofClicks'>&nbsp;</span>

这是代码

 function count_blocks() {

    var length = $("#questions > div").length;
    var ClickCounterViewModel = function () {
        this.totalnumberofClicks = ko.observable(length);
        this.numberOfClicks = ko.observable(1);
        this.registerClick = function () {
            this.numberOfClicks(this.numberOfClicks() + 1);
            if (numberOfClicks >= totalnumberofClicks ) {
                alert("error!");

            }
        };
    };
    ko.applyBindings(new ClickCounterViewModel());

}

当 numberOfClicks >=totalnumberofClicks 时，我需要收到警报。

但是我有错误

 Uncaught ReferenceError: numberOfClicks is not defined
    at ClickCounterViewModel.registerClick (2141:169)
    at HTMLButtonElement.<anonymous> (knockout-3.4.2.js:90)
    at HTMLButtonElement.dispatch (jquery-3.1.1.js:5201)
    at HTMLButtonElement.elemData.handle (jquery-3.1.1.js:5009)

我该如何解决这个问题？

Answer 1

this registerClick内仅是方法内的范围。通过将外部作用域变量绑定(bind)到 self 来访问外部作用域变量并将其用作:

var ClickCounterViewModel = function () {
    var self = this;
    this.totalnumberofClicks = ko.observable(length);
    this.numberOfClicks = ko.observable(1);
    this.registerClick = function () {
        self.numberOfClicks(self.numberOfClicks() + 1);
        if (self.numberOfClicks() >= self.totalnumberofClicks()) {
            alert("error!");
        }
    };
};