knockout "data-" attribute binding handler

ko.bindingHandlers.data.js

// Usage: 
//      <span data-bind="text: FromDate, data: { 'item' : ItemID}"></span>  => 'data-item' has ItemID() value
//      <span data-bind="text: FromDate, data: { 'value' : $data}"></span>  => 'data-value' will be rendered as JSON
//      <span data-bind="text: FromDate, data: { 'item' : ItemID, value' : $data}"></span> => more than one data attribute
//
// or something confusing as
//       <span data-bind="text: FromDate, data: ItemID, name: 'item'"></span>
 
 
ko.bindingHandlers.data = {
    name: ko.observable(''),
    update: function (element, valueAccessor, allBindingsAccessor) {
        var va = ko.utils.unwrapObservable(valueAccessor());
        var value = "", name = "";
        var d = {};
        if (typeof (va) === "object") {
            for (var k in va) {
                var _val = ko.utils.unwrapObservable(va[k]);
                if (typeof (_val) !== "object") {
                    d["data-" + k] = _val;
                } else {
                    d["data-" + k] = ko.toJSON(_val);
                }
            }
        } else {
            value = va;
            name = ko.utils.unwrapObservable(allBindingsAccessor().name !== undefined
                          ? allBindingsAccessor().name
                          : ko.bindingHandlers.data.name);
            d["data-" + name] = value;
        }



        ko.bindingHandlers.attr.update(element, function () {
            return d;
        });
    }
};