Using Knockout.js how do bind a Date property to a HTML5 date picker?

Question

(this only works in Chrome at the moment as most browsers don\'t yet implement date picker for input type=\"date\")

In the following example MyDate starts o

Answer 1

While @amakhrov answer will work (and would be even better if used writeable computed observable like sujested by @Stijn) I decided to do this using Custom Bindings.

The main advantage of doing this is reusability - I just have to use data-bind="datePicker : MyDate" whereever I want to tie this in. I can also modify other properties of the input element so this could be really useful if binding to complex jQuery (and other) controls.

(Read here for more pro/cons about the 3 choices to do this sort of thing)

HTML

<input data-bind="datePicker : MyDate" type="date">

JS

ko.bindingHandlers.datePicker = {
    init: function (element, valueAccessor, allBindingsAccessor, viewModel) {                    
        // Register change callbacks to update the model
        // if the control changes.       
        ko.utils.registerEventHandler(element, "change", function () {            
            var value = valueAccessor();
            value(new Date(element.value));            
        });
    },
    // Update the control whenever the view model changes
    update: function (element, valueAccessor, allBindingsAccessor, viewModel) {
        var value =  valueAccessor();        
        element.value = value().toISOString();
    }
};

var viewModel = {    
    MyDate : ko.observable(new Date())
};     

ko.applyBindings(viewModel);

See http://jsfiddle.net/LLkC4/5/

Answer 2

This worked for me

ko.bindingHandlers.momentDate = {
_parseDateTime: function (element, valueAccessor) {
    var value = valueAccessor();
    var valueUnwrapped = ko.utils.unwrapObservable(value);
    var datetime = moment(valueUnwrapped);
    var date = moment($(element).val(), 'YYYY-MM-DD');
    datetime = datetime.set({
        'year': date.get('year'),
        'month': date.get('month'),
        'date': date.get('date')
    });
    value(datetime.toDate());
},
init: function (element, valueAccessor) {
    function bind() {
        ko.bindingHandlers.momentDate._parseDateTime(element, valueAccessor);
    }
    $(element).change(bind).blur(bind);
},
update: function (element, valueAccessor) {
    var value = valueAccessor();
    var valueUnwrapped = ko.utils.unwrapObservable(value);
    var date = moment(valueUnwrapped);
    $(element).val(date.format('YYYY-MM-DD'));
}

};

<input type="date" data-bind="momentDate: $data.Date" class="form-control"/>