// JavaScript Document
var xmlHttp = false; 
try { 
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP"); 
} catch (e) { 
try { 
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); 
} catch (e2) { 
xmlHttp = false; 
} 
} 
if (!xmlHttp && typeof XMLHttpRequest != 'undefined') { 
xmlHttp = new XMLHttpRequest(); 
} 
function call_server() { 
var code = document.getElementById("code").value;
if (code == null || code == "") return;
if (code.length!=4){
    code_div.innerHTML="<table><tr><td><img src='images/reg_alert.jpg'></td><td><font color='red'> 验证码长度有误，请重新输入。</font></td></tr></table>";
	return false;
}
var url = "ajax_code.php?code=" + escape(code);
xmlHttp.open("GET", url, true); 
xmlHttp.onreadystatechange = update_Page; 
xmlHttp.send(null); 
} 
function update_Page() { 
if (xmlHttp.readyState < 4) { 
code_div.innerHTML="<font color='red'>检测验证码，请稍后……</font>"; 
} 
if (xmlHttp.readyState == 4) {
var response=xmlHttp.responseText;
   if (response=="0"){
   code_div.innerHTML="<table><tr><td><img src='images/reg_alert.jpg'></td><td><font color='red'> 验证码有误，请修正。</font></td></tr></table>";
   return false;
  }else{
  code_div.innerHTML="";
   return false;
  }
}
}