Knockout JS - Select2 Integration

knockout-select2.js

ko.bindingHandlers.select2 = {
    init: function (element, valueAccessor, allBindingsAccessor) {
        var obj = valueAccessor(),
            allBindings = allBindingsAccessor(),
            lookupKey = allBindings.lookupKey;
        var select2 = $(element).select2(obj);

        // Bind events
        if ("on" in obj) {
            for (var event in obj.on) {
                select2.on(event, obj.on[event]);
            }
        }

        if(allBindings.value){  // FIX no initial values
            allBindings.value.subscribe(function (v) {
                $(element).trigger('change');
            });
        }

        if (lookupKey) {
            var value = ko.utils.unwrapObservable(allBindings.value);
            $(element).select2('data', ko.utils.arrayFirst(obj.data.results, function (item) {
                return item[lookupKey] === value;
            }));
        }

        // The selected binding is similar to the value binding, but it is in array format and preserves the objects
        var selected = obj.selected;
        if (selected) {
            $(element).select2('data', ko.utils.unwrapObservable(selected));

            select2.on('change', function (e) {
                if (ko.isObservable(selected))
                    selected($(element).select2('data'));
            });
        }

        ko.utils.domNodeDisposal.addDisposeCallback(element, function () {
            $(element).select2('destroy');
        });
    },
    update: function (element, valueAccessor, allBindingsAccessor) {
        var allBindings = allBindingsAccessor();

        // If we have a selected binding, update the select2 to reflect any changes (creates a dependency on the observable)
        var selected = ko.utils.unwrapObservable(valueAccessor().selected);
        if (selected) {
            $(element).select2('data', selected);
        }

        $(element).trigger('change');
    }
};