最简单的一个ajax应用，框架什么的还没去研究呢，记录着先

// ************ ajax function findAuthor(url) { var xmlObj = null; if(window.XMLHttpRequest) { xmlObj = new XMLHttpRequest(); } else if(window.ActiveXObject) { xmlObj = new ActiveXObject("Microsoft.XMLHTTP"); } else { return; } xmlObj.onreadystatechange = function() { getObj('username_signal').innerHTML = "LOADING..."; if(xmlObj.readyState == 4) { //var see = xmlObj.responseXML.getElementsByTagName('name')[0].firstChild.data; var see = xmlObj.responseText; //alert(see); //alert(see==1); if(see==1) { //when 1 , user not exist in db getObj('username_signal').innerHTML = "用户名可以使用！"; username_signal = true; } else { //when 0 , user has existed in db getObj('username_signal').innerHTML = "用户名已经被使用，换一个吧！"; username_signal = false; } } } xmlObj.open ('GET', url, true); xmlObj.send (''); }