<!DOCTYPE html> 
 <html> 
 <head> 
     <meta charset="UTF-8">
     <title>calc_AJAX.html</title> 
  <script type="text/javascript">
  function loadXMLDoc(number1,number2)
  {
  var xmlhttp;
  if (window.XMLHttpRequest)
    {// code for IE7+, Firefox, Chrome, Opera, Safari
    xmlhttp=new XMLHttpRequest();
    }
  else
    {// code for IE6, IE5
    xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    }   xmlhttp.onreadystatechange=function()
    {
    if (xmlhttp.readyState==4 && xmlhttp.status==200)
   {
   document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
   }
    }    var url="calc_AJAX_GET.php?num1="+number1+"&num2="+number2; //请求字符串
  xmlhttp.open("GET",url,true);
  xmlhttp.send();
  }
  </script>
 </head>
 <body>   
<form method="post" action="">
 计算器<br>
 数值1：<input type="text" id="num1" value="3"> <br>
 数值2：<input type="text" id="num2" value="2"> <br>
 <br>
 <button type="button" name="add" value="+" οnclick="loadXMLDoc(document.getElementById('num1').value, document.getElementById('num2').value)">+ </button>
 <br>
 结果：<br>
 <div id="myDiv"><h3>Let AJAX change this text</h3></div>
 </form>
 </body> 
 </html>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 <html>
  <head>
     <title>calc_AJAX_GET.php</title>
     <meta charset="UTF-8">
  </head> <body>
       <?php
     $sum="";
    $num1=isset($_GET['num1']) ? $_GET['num1'] : ""; 
    $num2=isset($_GET['num2']) ? $_GET['num2'] : "";if(is_numeric($num1) && is_numeric($num2)){ 
     $sum=$num1+$num2; 
 }else{     echo "请输入有效数值"; 
  exit(0);} 
 echo $sum;
 ?> 
  </body>
 </html>