Knockout.js .slideDown() binding with jQuery

slideToggle.js

// Here's a custom Knockout binding that makes elements shown/hidden via jQuery's slideDown()/slideUp() methods
// Could be stored in a separate utility library
ko.bindingHandlers.slideToggle = {
    init: function(element, valueAccessor) {
        // Initially set the element to be instantly visible/hidden depending on the value
        var value = valueAccessor();
        $(element).toggle(ko.utils.unwrapObservable(value)); // Use "unwrapObservable" so we can handle values that may or may not be observable
    },
    update: function(element, valueAccessor) {
        // Whenever the value subsequently changes, slowly slide the element down or up
        var value = valueAccessor();
        ko.utils.unwrapObservable(value) ? $(element).slideDown() : $(element).slideUp();
    }
};