文章来自 codego.net 请看源代码:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "">
 <html xmlns="">
 <head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>计算器</title>
<script language="javascript" type="text/javascript">
 var clearFlag=false;
 function getNum(num){
 //alert(num);
  var objresult=document.getElementById("result");
  if(clearFlag){
   objresult.value="";
   clearFlag=false;
  }
 //alert(objresult);
 objresult.value+=num;
 }
function getResult(){
 var objresult=document.getElementById("result");
 objresult.value=objresult.value+"="+eval（objresult.value);
 clearFlag=true;
}
</script>
</head&gt,-codego.net-;
<body>
<table width="200" border="1" cellpadding="2">
  <tr>
    <td colspan="4"><input type="text" name="result" id="result" size="33"></td>
  </tr>
  <tr>
    <td width="56"><input type="button" value="  1   " onclick="getNum(1)"></td>
    <td width="56"><input type="button" value="  2   " onclick="getNum(2)"></td>
    <td width="51"><input type="button" value="  3   " onclick="getNum(3)"></td>
    <td width="58"><input type="button" value="  +   " onclick="getNum('+')"></td>
  </tr>
  <tr>
    <td><input type="button" value="  4   " onclick="getNum(4)"></td>
    <td><input type="button" value="  5   " onclick="getNum(5)"></td>
    <td><input type="button" value="  6   " onclick="getNum(6)"></td>
    <td><input type="button" value="  -   " onclick="getNum('-')"></td>
  </tr>
  <tr>
    <td><input type="button" value="  7   " onclick="getNum(7)"></td>
    <td><input type="button" value="  8   " onclick="getNum(8)"></td>
    <td><input type="button" value="  9   " onclick="getNum(9)"></td>
    <td><input type="button" value="  *   " onclick="getNum('*')"></td>
  </tr>
  <tr>
    <td><input type="button" value="  0   " onclick="getNum(0)"></td>
    <td><input type="button" value="  .   " onclick="getNum('.')"></td>
    <td><input type="button" value="  =   " onclick="getResult()"></td>
    <td><input type="button" value="  /   " onclick="getNum('/')"></td>
  </tr>
</table>
</body>
</html>