A jQuery method for switching classes in the DOM

jquery.switchclasses.js

define([
    'jquery'
], function ($) {
    "use strict";

    /**
     * Method for switching between 2 or multiple classes
     * @param  {String} currentClasses  The classes that currently exists
     * @param  {String} newClasses      The classes we want to change to
     * @param  {Mixed} [expression]     Expression/callback that will be evaluated.
     *                                  If it's true, it will apply the rules.
     *
     * @return {jQuery DomObject}
     */
    $.fn.switchClasses = function(currentClasses, newClasses, expression) {

        return this.each(function(){
            var $this = $(this),
                resultExpression = void 0;

            if ($.isFunction(expression)) {
                resultExpression = !!expression.call(this, currentClasses, newClasses);
            }
            else if (typeof expression === 'boolean') {
                resultExpression = expression;
            }
            else if (typeof expression === 'undefined') {
                resultExpression = true;
            }
            
            if (resultExpression) {
                $this.removeClass(currentClasses).addClass(newClasses);
            }
            else {
                $this.addClass(currentClasses).removeClass(newClasses);
            }
        });
    };

    return $;
});