JavaScript实现简易网页计算器的完整代码示例

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<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>
<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>

补充说明：此处推荐本站两款基于js实现的在线计算器，功能强大，有助于深入理解JavaScript数学运算及web设计：

在线标准计算器：http://tools.jb51.net/jisuanqi/jsq

在线科学计算器：http://tools.jb51.net/jisuanqi/jsqkexue