根据 ScrollectBox ，你必须使用 onSelectEvent 属性，如下所示：

According to the source code for ScrollectBox, you must use the onSelectEvent property, like so:

jQuery(document).ready(function($){ 
    $(".selection").scrollectBox({
        preset: 'dropdown',
        numVisibleOptions: 4,
        scrollInterval: 150, 
        scrollOn: 'hover',
        onSelectEvent: function (item, event) {
           alert(item.val());
        }
    });
});