AJAX实例：根据邮编自动完成地址信息

描述：

在注册或购物车结帐的时候，需要用户填入个人资料，这个环节可以简练一下，我们只需客人填入邮政编码，然后就根据这个邮政编码，自动从数据库中取出相应的省，市等地址信息。这样既可以减少客户的输入，增加客户体验，又可以减少由于资料输入而产生的错误。

实现：

HTML
＜script>
function createRequestObject() {
var ro;
var browser = navigator.appName;
if(browser == "Microsoft Internet Explorer"){
ro = new ActiveXObject("Microsoft.XMLHTTP");
}else{
ro = new XMLHttpRequest();
}
return ro;
}
var http = createRequestObject();
function sndReq(zip) {
http.open('get', 'zipcode.php?zip='+zip);
http.onreadystatechange = handleResponse;
http.send(null);
} function handleResponse() {
if(http.readyState == 4){
var response = http.responseText;
var update = new Array();
if(response.indexOf('|' != -1)) {
update = response.split('|');
document.getElementById("city").value = update[0];
document.getElementById("state").value = update[1];
}
}
}
＜/script>
＜h3>Enter A United States Zipcode, Then Tab＜/h3>
＜table align="center">
＜tr>
＜td>Enter Zipcode:＜/td>
＜td>＜input type="text" id="zipcode" name="zipcode" onBlur="sndReq(this.value);"/>＜/td>
＜/tr>
＜tr>
＜td>City:＜/td>
＜td>＜input type="text" id="city" name="city"/>＜/td>
＜/tr>
＜tr>
＜td>State:＜/td>
＜td>＜input type="text" id="state" name="state"/>＜/td>
＜/tr>
＜/table>
以上是客户输入页面，下面是服务端的处理页面'zipcode.php

$dbuser = 'root';
$dbpass = '111111';
$cn = mysql_connect("localhost", $dbuser, $dbpass);
$db = mysql_select_db("ajax");
$sql = "select city, state from zipcodes where zipcode = " .