references third-party plug-ins encapsulated by jquery in vue.
plug-ins are functions encapsulated by jauery extensions

$.fn.xs999 = function(u, g) {
        y = {
            color: false,
        }
        $.extend(y, g);
        $(this).each(function() {
            new b($(this), u, y);
        });
    }

use $(") in the vue component. Xs999 (); prompts xs999 is not defined
what to do?