knockout animation on class change

ko.animated-css.js

var classesWrittenByBindingKey = '__ko__cssValue';
ko.bindingHandlers.animatedCss = {
    'update': function (element, valueAccessor) {
        var value = ko.utils.unwrapObservable(valueAccessor());
        if (typeof value == "object") {

            var currentClassList = element.className.split(/\s+/);
            var removeClassList = [];
            var addClassList = [];

            for (var className in value) {
                var shouldHaveClass = ko.utils.unwrapObservable(value[className]);
                var haveClass = $.inArray(className, currentClassList) > 0;
                
                if (haveClass && !shouldHaveClass) {
                    removeClassList.push(className);
                } else if (!haveClass && shouldHaveClass) {
                    addClassList.push(className);
                }
            }

            var removeClasses = removeClassList.join(" ");
            var addClasses = addClassList.join(" ");

            $(element).switchClass(removeClasses, addClasses, 1000);

        } else {
            value = String(value || ''); // Make sure we don't try to store or set a non-string value
            ko.utils.toggleDomNodeCssClass(element, element[classesWrittenByBindingKey], false);
            element[classesWrittenByBindingKey] = value;
            ko.utils.toggleDomNodeCssClass(element, value, true);
        }
    }
};