jQuery Simple Add Option ComboBox

jquery.combobox.js

(function($) {
    $.fn.comboBox = function () {
        var $this = $(this);
        return $this.on("change", function(){
            if ( $this.val() === 'add' ) {
                $("<input type='text' />").blur(function(e) {
                    e.preventDefault();
                    var $i = $(this),
                        val = $i.val(),
                        selected = $this.find("option:contains('" + ucWord(val) + "')");
                    
                    if (!selected.length) {
                        $("<option>", {
                            value: val,
                            text: val
                        }).insertBefore($this.find("option").last());
                    }
                    $this.val( selected.length ? selected.val() : val );
                    $i.empty().remove();
                    $this.show();
                }).insertAfter( $this.hide() ).focus();
            }
        });
    };
    
    function ucWord( str ) {
        return str.charAt(0).toUpperCase() + str.slice(1);
    }
 })(jQuery);

// Usage: $('select').comboBox();