javascript - KnockoutJS 将时间戳拆分为月份下拉列表和年份文本输入

Question

如何设法处理最初为空的时间戳？我需要按步骤设置月份和年份。下拉列表中的月份和文本输入字段中的年份。

在这里摆弄:http://jsfiddle.net/DrHyper/azf74/

JS:

function AgreementData(data) {
var self = this;
data = data || {};


self.effectiveDate = ko.observable(data.effectiveDate || "");
self.effectiveDateMonth = ko.computed({
    read: function () {
        var dateR = new Date(self.effectiveDate());
        return dateR.getMonth();
    },
    write: function (value) {
        var dateW = new Date(self.effectiveDate());
        dateW.setMonth(value);
        self.effectiveDate(dateW.getTime());
    },
    owner: self
});
self.effectiveDateYear = ko.computed({
    read: function () {
        var dateR = new Date(self.effectiveDate());
        return dateR.getFullYear() ? dateR.getFullYear() : "";
    },
    write: function (value) {
        var dateW = new Date(self.effectiveDate());
        dateW.setFullYear(value);
        self.effectiveDate(dateW.getTime());
    }
});
}

var Month = function (monthIndex, monthString) {
this.monthIndex = monthIndex;
this.monthString = monthString;
};

function AgreementViewModel() {
var self = this;
self.agreement = ko.observable(new AgreementData());
self.months = ko.observableArray([new Month(0, 'Januar'), new Month(1, 'Februar'), 
new Month(2, 'Marts'), new Month(3, 'April'), new Month(4, 'Maj'), 
new Month(5, 'Juni'), new Month(6, 'Juli'), new Month(7, 'August'), 
new Month(8, 'September'), new Month(9, 'Oktober'), new Month(10, 'November'), 
new Month(11, 'December')]);

//    self.postAgreement = function () {
//        var jsonData = ko.toJSON(self.agreement);
//        $.post("/sam-rest/agreements", jsonData, function(returnedData) {
//            // This callback is executed if the post was successful
//        })
//
//    };
//
//    self.getAgreement = function (agreementNumber) {
//        $.getJSON("/sam-rest/agreements/"+agreementNumber, function (jsonData) {
//            self.agreement(new AgreementData(jsonData));
//        });
//
//    };
//
//    Sammy(function() {
//            this.get('#:action/:agreementNmb', function() {
//                self.action(this.params.action);
//                self.getAgreement(this.params.agreementNmb);
//            });
//    }).run();

}

var agreementViewModel = new AgreementViewModel();
ko.applyBindings(agreementViewModel);

HTML:

<form>
Month: <select id="effectiveDateMonth" data-bind="options: months,
                     optionsText: 'monthString',
                     optionsValue: 'monthIndex',
                     value: agreement().effectiveDateMonth,
                     optionsCaption: 'Choose...'"></select>
Year: <input type="text" data-bind="value: agreement().effectiveDateYear" placeholder="YYYY" />
<hr>
</form>

Answer 1

您可以创建像 observableDate 这样的东西，将月份和年份共享为可观察的:

ko.observableDate = function (value) {
    var month = ko.observable(null);
    var year = ko.observable(null);
    var date = ko.computed({
        read: function() {
            if (year() !== null && month() !== null) {
                return new Date(year(), month(), 1);
            }
            else {
                return null;
            }
        },
        write: function (date) {
            if (date) {
                month(date.getMonth());
                year(date.getYear());
            }
            else {
                month(null); 
                year(null);
            }
        }
    });
    date(value);
    date.year = year;
    date.month = month;

    return date;
};

然后绑定(bind)到年和月:

<form>
Month: <select id="effectiveDate.month" data-bind="options: months,
                     optionsText: 'monthString',
                     optionsValue: 'monthIndex',
                     value: agreement().effectiveDate.month,
                     optionsCaption: 'Choose...'"></select>
Year: <input type="text" data-bind="value: agreement().effectiveDate.year" placeholder="YYYY" />
<hr>
</form>

完整示例:http://jsfiddle.net/UXjBf/7/