knockout.js - jQuery UI datepicker change event not caught by KnockoutJS

Question

I'm trying to use KnockoutJS with jQuery UI. I have an input element with a datepicker attached. I'm currently running knockout.debug.1.2.1.js and it seems that the change event is never being caught by Knockout. The element looks like this:

<input type="text" class="date" data-bind="value: RedemptionExpiration"/>

I've even tried changing the valueUpdate event type but to no avail. It seems like Chrome causes a focus event just before it changes the value, but IE doesn't.

Is there some Knockout method that "rebinds all the bindings"? I technically only need the value changed before I send it back to the server. So I could live with that kind of workaround.

I think the problem's the datepicker's fault, but I can't figure out how to fix this.

Any ideas?

Answer 1

I think that for the jQuery UI datepicker it is preferable to use a custom binding that will read/write with Date objects using the APIs provided by the datepicker.

The binding might look like (from my answer here):

ko.bindingHandlers.datepicker = {
    init: function(element, valueAccessor, allBindingsAccessor) {
        //initialize datepicker with some optional options
        var options = allBindingsAccessor().datepickerOptions || {},
            $el = $(element);

        $el.datepicker(options);

        //handle the field changing by registering datepicker's changeDate event
        ko.utils.registerEventHandler(element, "changeDate", function () {
            var observable = valueAccessor();
            observable($el.datepicker("getDate"));
        });

        //handle disposal (if KO removes by the template binding)
        ko.utils.domNodeDisposal.addDisposeCallback(element, function() {
            $el.datepicker("destroy");
        });

    },
    update: function(element, valueAccessor) {
        var value = ko.utils.unwrapObservable(valueAccessor()),
            $el = $(element);

        //handle date data coming via json from Microsoft
        if (String(value).indexOf('/Date(') == 0) {
            value = new Date(parseInt(value.replace(//Date((.*?))//gi, "$1")));
        }

        var current = $el.datepicker("getDate");

        if (value - current !== 0) {
            $el.datepicker("setDate", value);
        }
    }
};

You would use it like:

<input data-bind="datepicker: myDate, datepickerOptions: { minDate: new Date() }" />

Sample in jsFiddle here: http://jsfiddle.net/rniemeyer/NAgNV/