<!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>无标题文档</title>
<link href="calc.css" rel="stylesheet" type="text/css" />
<script type="text/javascript" language="javascript">
//计算机累加总数，表示第一个数
var sum =0;
//第二个数
var num1 =0;
//操作符
var oper; function getBtn(obj){ var res = document.getElementById("display");
switch(obj.value){
case "1":
//连着按数字，拼接字符串，例如：111
res.value += obj.value;
break;
case "2":
res.value += obj.value;
break;
case "3":
res.value += obj.value;
break;
case "4":
res.value += obj.value;
break;
case "5":
res.value += obj.value;
break;
case "6":
res.value += obj.value;
break;
case "7":
res.value += obj.value;
break;
case "8":
res.value += obj.value;
break;
case "9":
res.value += obj.value;
break;
case "0":
res.value = parseInt(0);
break;
case "+":
//获取用户按的第一个数字和操作符
getOperAndNum2Value((parseInt(res.value)),"+");
break;
case "-":
getOperAndNum2Value((parseInt(res.value)),"-");
break;
case "*":
getOperAndNum2Value((parseInt(res.value)),"*");
break;
case "/":
getOperAndNum2Value((parseInt(res.value)),"/");
break;
case "=":
//获取用户当前按的第二个数字
num1 = parseInt(res.value);
//调用函数计算结果
showResult(sum,num1,oper);
break;
case "POWER":
sum = parseInt(res.value);
//一个数的N次方，开方
sum *=sum;
document.getElementById("display").value = sum;
break;
case "Clear":
document.getElementById("display").value = "";
break;
case "Back":
sum = res.value;
if(sum.length>0){
sum = parseInt(sum.substring(0,sum.length-1));
document.getElementById("display").value = sum;
}
break;
default:
window.alert("没有这个按键！");
break;
}
} //计算结果
function showResult(num1,num2,op){
switch(op){
case "+":
sum = num1 + num2;
break;
case "-":
sum = num1 -num2;
break;
case "*":
sum = num1 * num2;
break;
case "/":
if(num1!=0){
sum = num1 / num2;
}
}
document.getElementById("display").value = sum;
} //给操作符和第一个数赋值,点击操作符号后，清空显示栏
function getOperAndNum2Value(num2,op){
oper = op;
sum = parseInt(num2);
document.getElementById("display").value ="";
}
</script>
</head> <body>
<table width="250" border="1" cellspacing="0" cellpadding="0">
<tr style="background-color:#000099">
<td colspan="4" align="center"><input type="text" id="display" class="show"/></td>
</tr>
<tr>
<td width="63"><input type="button" value="POWER" onclick="getBtn(this)" /></td>
<td width="63"><input type="button" value="Clear" onclick="getBtn(this)"/></td>
<td width="63"><input type="button" value="Back" onclick="getBtn(this)"/></td>
<td width="51"> </td>
</tr>
<tr>
<td><input type="button" value="1" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="2" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="3" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="4" class="button" onclick="getBtn(this)"/></td>
</tr>
<tr>
<td><input type="button" value="5" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="6" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="7" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="8" class="button" onclick="getBtn(this)"/></td>
</tr>
<tr>
<td><input type="button" value="9" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="0" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="." class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="=" class="button" onclick="getBtn(this)"/></td>
</tr>
<tr>
<td><input type="button" value="+" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="-" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="*" class="button" onclick="getBtn(this)"/></td>
<td><input type="button" value="/" class="button" onclick="getBtn(this)"/></td>
</tr>
</table>
</body>
</html>
calc.css
/* CSS Document */
.show{
width:140px;
height:20px;
} .button{
width:58px;
}
计算器界面如下：