jq 查找多個 find('.dot, .triangle, .textcon')

var $target = $container.children().last();
$target.find('.dot, .triangle, .textcon').each(function (i, n) {
    var $this = $(n);
    switch(n.className) {
        case 'dot':
            $this.addClass('error-dot');
            break;
        case 'triangle':
            $this.addClass('error-triangle');
            break;
        case 'textcon':
            $this.addClass('error-textcon');
            break;
    }
});