jQuery对象和DOM对象 √
http://www.ituring.com.cn/article/38868
<!DOCTYPE html> <html lang="zh-CN"> <head> <meta charset="utf-8"> <title></title> </head> <body> <ul> <li>item</li> <li>item</li> </ul> <script src="http://static01.baomihua.com/js/lib/jquery-1.4.4.min.js?t=20120926.js"></script> <script> var aElem = $('a') var liElem = $('li') console.log(aElem) console.log(aElem.length) console.log(aElem[0]) console.log(liElem) console.log(liElem.length) console.log(liElem[0], liElem[1]) aElem.click(function() { }) if (aElem[0]) { } var aElem = document.getElementsByTagName('a')[0] var liElem = document.getElementsByTagName('li')[0] console.log(aElem) console.log(liElem) if (aElem) { aElem.onclick = function() { } } liElem.onclick = function() { } function getElem(elem) { return document.getElementsByTagName(elem)[0] || document.createElement(elem) // 这样处理不报错了，jQuery怎么处理？ } getElem('a').onclick = function() { } </script> </body> </html>