function dir(elem, dir, until) {??? //這個(gè)dir怎么理解？until呢？
? var matched = [],
??? truncate = until !== undefined;
? while ((elem = elem[dir]) && elem.nodeType !== 9) {?
??? if (elem.nodeType === 1) {
????? if (truncate) {
??????? if (elem.nodeName.toLowerCase() == until || elem.className == until) {
????????? break;
??????? }
????? }
????? matched.push(elem);
??? }
? }
? return matched;
}

? jQuery.each({
??? parent: function(elem) {
????? var parent = elem.parentNode;
????? return parent && parent.nodeType !== 11 ? parent : null;
??? },
??? parents: function(elem) {
????? return dir(elem, "parentNode");
??? },
??? parentsUntil: function(elem, until) {
????? return dir(elem, "parentNode", until);
??? }
? }, function(name, fn) {
??? ajQuery[name] = function(until, selector) {
????? return? fn(until, selector);
??? };
? });