点击“=”没反应，不知道问题出在那里。
<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var num1 = document.getElementById("txt1").value
var num2 = document.getElementById("txt2").value
var select = document.getElementById("select").value
var result="";
switch(select){
case "+":
result=parseFolat(num1)+parseFolat(num2);
break;
case "-":
result=parseFolat(num1)-parseFolat(num2);
break;
case "*":
result=parseFolat(num1)*parseFolat(num2);
break;
default "/":
result=parseFolat(num1)/parseFolat(num2);
}
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>
