简单的ajax 使用demo。
同时还会回馈给前台。
<script type="text/javascript">
function Createregxml() {
try {
regxml = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
try {
regxml = new ActiveXObject("Msxm12.XMLHTTP");
} catch (E) {
regxml = false;
}
}
if (!regxml && typeof XMLHttpRequest != 'undefined') {
regxml = new XMLHttpRequest();
}
return regxml;
}
function returnI() {
if (regxml.readyState == 4) {
var Data = regxml.responseText;
// alert(Data);
var str = Data.substring(0,3);
//alert(str);
if (str == "yes") {
var divobj = document.getElementById("divusername");
divobj.innerHTML = "<font color=greed>√</font>可以注册检查通过。";
} else {
var divobj = document.getElementById("divusername");
divobj.style.display = "block";
divobj.innerHTML = "<font color=red>×</font>这个用户名已经被注册了，请换一个";
}
}
}
function chcek() {
var username = document.getElementById("username").value;
alert(username);
regxml = Createregxml();
regxml.onreadystatechange = returnI;
var url = "service.jsp?";
regxml.open("post",url + "username=" + username);
regxml.send(null);
}
</script>
<body> <input type="text" name="username" id="username" onblur="chcek()"> <div id="divusername"></div> </body>
service.jsp
<%
String username = request.getParameter("username");
System.out.println(username);
out.clear();
if ("chen".equals(username)) {
out.print("no");
} else {
out.print("yes");
}
%>
原文链接：https://www.f2er.com/ajax/166501.html