利用ajax+php实现商品价格计算

!DOCTYPE html>
html>

head>
 meta charset="utf-8" />
 title>商品价格计算/title>
 style type="text/css">
 table {
 border-collapse: collapse;
 }

 tr {
 text-align: center;
 }

 .a4 {
 text-align: right;

 /* padding-right: 15px; */
 }

 #myDiv {
 color: red;
 }

 input {
 border: 0;
 }
 /style>
/head>

body>
 form action="data.php" method="get">
 table border="1" bordercolor="#00CCCC" cellpadding="20">
 tr>
 th>商品名称/th>
 th>购买数量（斤）/th>
 th>商品价格（元/斤）/th>
 /tr>
 tr>
 td>香蕉/td>
 td>input type="text" name="a1" value="0" id="n1" onchange="zongji()" />/td>
 td>8/td>
 /tr>
 tr>
 td>苹果/td>
 td>input type="text" name="a2" value="0" id="n2" onchange="zongji()" />/td>
 td>5/td>
 /tr>
 tr>
 td>橘子/td>
 td>input type="text" name="a3" value="0" id="n3" onchange="zongji()" />/td>
 td>7/td>
 /tr>
 tr>
 td colspan="3" class="a4">商品折扣：span>0.8/span>/td>
 /tr>
 tr>
 td colspan="3" class="a4">
  div id="jiage">打折后购买商品总价格: 元/div>
 /td>
 /tr>
 /table>


 /form>


 script>
 function zongji() {
 var b1 = document.getElementById("n1").value;
 var b2 = document.getElementById("n2").value;
 var b3 = document.getElementById("n3").value;
 //1.创建对象
 var xmlhttp;
 if (window.XMLHttpRequest) {
 // IE7+, Firefox, Chrome, Opera, Safari 浏览器执行代码
 xmlhttp = new XMLHttpRequest();
 } else {
 // IE6, IE5 浏览器执行代码
 xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
 }
 //2.判断对象是否准备就绪
 xmlhttp.onreadystatechange = function() {
 if (xmlhttp.readyState == 4  xmlhttp.status == 200) {
  document.getElementById("jiage").innerHTML = xmlhttp.responseText;
 }
 };
 //3.发出请求
 xmlhttp.open(
 "GET",
 "demo.php?c1=" + b1 + "c2=" + b2 + "c3=" + b3,
 true
 );
 xmlhttp.send();
 }
 /script>
/body>

/html>

p>
 ?php
 $d1 = $_GET["c1"];
 $d2 = $_GET["c2"];
 $d3 = $_GET["c3"];
 $sum = (intval($d1) * 8 + intval($d2) * +intval($d3) * 7) * 0.8;
 // $sum=$a1*7.99+$a2*6.89+$a3*3.99;
 echo "打折后购买商品总价格: $sum 元";
 ?>
/p>