javascript进阶6-11编程的程序？？？
<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var v1 = parseInt(document.getElementById('txt1').value);
//获取第一个输入框的值
var v2 = parseInt(document.getElementById('txt2').value);
//获取第二个输入框的值
var fuhao = document.getElementById('select').value;
var result= '';
//获取选择框的值
switch(fuhao)
{
case '+': result = v1+v2;break;
case '-': result = v1-v2;break;
case '*': result = v1*v2;break;
case '/': result = v1/v2;break;
}
//获取通过下拉框来选择的值来改变加减乘除的运算法则
//document.write("shuchu");
//window.alert(shuchu);
//return shuchu;
//设置结果输入框的值
document.getElementById('fruit').value=result;
}
</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>