Knockout and jQuery Mobile: Checkboxes

Question

I'm trying to dynamically add checkbox and label elements to the document. Checkbox element has Knockout's data-bind attribute to bind its value to an observable value in the ViewModel. However when I try to style the checkboxes with jQuery Mobile by executing

$('input[type="checkbox"]').checkboxradio();

data-bind attributes will be removed. If I leave out the above line, data-bind attributes are properly set and the binding works.

Is there a way to have both jQuery Mobile styling and Knockout bindings at the same time?

I'm using jQuery Mobile RC1 and Knockout 1.2.1.

Answer 1

There is a problem with using knockouts default checked binding with styled objects like jQuery mobile does. It has the same issues that jQueryUi's Button/Buttonset functions. There is a label over the checkbox that indicates what is happening and it doesn't get updated properly via standard knockout checked binding.

It is discussed at http://therunningprogrammer.blogspot.com/2011/10/how-to-use-jquery-uis-button-with.html.

To use knockout directly with these styled objects from jQuery Mobile, the demonstrated code will have to be modified to handle the different DOM context. I'll post an update to the code when I can get some free time to do it.

EDIT

In Google Groups - Knockout, luv2hike posted a solution. You can see it working at http://jsfiddle.net/luv2hike/nrJBC/. Looks like a working fix for your problem.

Answer 2

Here is my heavily commented code on a custom handler I built for jQueryMobile checkboxes:

ko.bindingHandlers.checkbox = {
init: function(element, valueAccessor) {

    // set the dom element to a checkbox and initialize it (for jquerymobile)
    var checkbox = $(element);
    checkbox.checkboxradio();
    checkbox.attr('type', 'checkbox');

    // register change event to update the model on changes to the dom
    ko.utils.registerEventHandler(element, "change", function() {
        valueAccessor()(

            // off because it is before the ui has refreshed
            $(this).siblings('label.ui-checkbox-off').length > 0
        );
    });
},
update: function(element, valueAccessor) {

    // update the checked binding, i.e., check or uncheck the checkbox
    ko.bindingHandlers.checked.update(element, valueAccessor)

    // and refresh the element (for jquerymobile)
    var checkbox = $(element);
    checkbox.checkboxradio('refresh')
}
};

Answer 3

I have also encountered this problem. Unfortunately, all the suggestions here either did not work for me or had other issues. So I have created a simple custom binding that works in all versions of KO (including the latest v3):

ko.bindingHandlers.jqmChecked = {
    init: ko.bindingHandlers.checked.init,
    update: function (element, valueAccessor) {
        //KO v3 and previous versions of KO handle this differently
        //KO v3 does not use 'update' for 'checked' binding
        if (ko.bindingHandlers.checked.update) 
            ko.bindingHandlers.checked.update.apply(this, arguments); //for KO < v3, delegate the call
        else 
            ko.utils.unwrapObservable(valueAccessor()); //for KO v3, force a subscription to get further updates

        if ($(element).data("mobile-checkboxradio")) //calling 'refresh' only if already enhanced by JQM
            $(element).checkboxradio('refresh');
    }
};

Should be used like this:

<input type="checkbox" data-bind="jqmChecked: someValue" id="checkbox1"/>

See a complete working example here:

http://jsfiddle.net/srgstm/ub6sq/

Answer 4

I created a simple binding that works with jQuery Mobile 1.2.0 and Knockout 2.2.1 and works with default jQuery mobile checkboxes. This binding has no dependency on custom icons or JQuery Mobile's CSS styles. It also allows the use of regular checkbox markup in your HTML (<input type="checkbox" ... />) as opposed to using an alternate markup element like a div.

Here's the fiddle: http://jsfiddle.net/thedude458/52baX/

Note: Presently, the example only supports a single checkbox, not a list, as that is all I currently have a need for. It also assumes that the bound property is an observable.

Answer 5

See: https://gist.github.com/1006808

Then you can do something like the following:

var $checkbox = $('input[type="checkbox"]');
$checkbox.checkboxradio();
$checkbox.dataBind({
    your options..
});

Hope this'll help!