<!DOCTYPE html>
<html lang="zh-cmn-Hans">
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=Edge,chrome=1">
<title>事件</title>
<meta name="keywords" content="关键词列表" />
<meta name="description" content="网页描述" />
<link rel="stylesheet" type="text/css" href="" />
<!--<script type="text/javascript" src="JS文件路径"></script>-->
<script type="text/javascript">
function count(){
//获取第一个输入框的值
//获取第二个输入框的值
//获取选择框的值
//获取通过下拉框来选择的值来改变加减乘除的运算法则
//设置结果输入框的值
var a = document.getElementById("txt1").value;
var b = document.getElementById("txt2").value;
var c = document.getElementById("select").value;
var d = '';
switch(c)
{
case "+":
d = a + b;
break;
case "-":
d= a - b;
break;
case "*":
d = a * b;
break;
case "/":
d = a / b;
break;
}
document.getElementById('fruit').value = d;
}
</script>
</head>
<body>
<input type="text" id="txt1" />
<select id="select">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select>
<input type="text" id="txt2" />
<input type="button" value="=" onclick="count()" /> <!-- 通过 = 按钮来调用创建的函数,得到结果 -->
<input type="text" id="fruit" />
</body>
</html>
除了加法 其他的都正常
