如何在jquery中向现有url添加查询字符串对

// custom :external selector
$.expr[':'].external = function(obj){
    return !obj.href.match(/^mailto\:/)
            && (obj.hostname != location.hostname);
};

// put the new querystring pair on every external link
$("a:external").each(function() {
     $(this).attr("href", $(this).attr("href") + "?aid=1234567");
});