求大神帮忙看看哪里出错了，没有输出_(:з」∠)_
<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var a=parseInt(document.getElementById('txt1').value);
var b=parseInt(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;
default:
d=a/b;
}
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>
