标签：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>简单计算器效果</title>
</head>
<body>
<form name="myForm">
数字1：<input type="text" name="num1" />
<br>
数字2：<input type="text" name="num2" />
<br>
结 果：<input type="text" name="res"/>
</form>
<br>
<button onclick="Calculation(‘+‘)">+</button>
<button onclick="Calculation(‘-‘)">-</button>
<button onclick="Calculation(‘*‘)">*</button>
<button onclick="Calculation(‘/‘)">/</button>
<script type="text/javascript">
function Calculation(e){
var num1 = document.myForm.num1.value;
var num2 = document.myForm.num2.value;
var res = null;
// 转换为数字，并验证合法性
num1 = parseFloat(num1);
num2 = parseFloat(num2);
if(isNaN(num1)){
alert(‘数字1不合法，请填写为数字‘);
return false;
}
if(isNaN(num2)){
alert(‘数字2不合法，请填写为数字‘);
return false;
}
// 计算结果
switch(e){
case ‘+‘:
res = num1 + ‘+‘ + num2 + "=" + (num1 + num2);
break;
case ‘-‘:
res = num1 + ‘-‘ + num2 + "=" + (num1 - num2);
break;
case ‘*‘:
res = num1 + ‘*‘ + num2 + "=" + (num1 * num2);
break;
case ‘/‘:
if(num2 == 0){
alert(‘数字2不能为零‘);
return false;
}
res = num1 + ‘/‘ + num2 + "=" + (num1 / num2);
break;
}
// 将结果写入结果框内
document.myForm.res.value = res;
}
</script>
</body>
</html>
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原文地址：http://my.oschina.net/mpf/blog/526860
