<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</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>
<script type="text/javascript">
//制做简单计算器
function count() {
var txt1 = document.all.txt1.value;
var txt2 = document.all.txt2.value;
var s=document.all.select.value;
var z;
switch(s){
case "+": z=parseFloat(txt1)+parseFloat(txt2);break;
case "-":
z=parseFloat(txt1)-parseFloat(txt2);break;
case "*":z=parseFloat(txt1)*parseFloat(txt2);break;
case "/":z=parseFloat(txt1)/parseFloat(txt2);break;
}
document.getElementById("fruit").value=z;
}
</script>
</html>