                        課程
                    
                        /前端開發
                        
                            /JavaScript
                        
                        /JavaScript進階篇

請問這個代碼有什么問題？

<!DOCTYPE?html>
<html>
?<head>
??<title>?事件</title>??
??<script?type="text/javascript">
??var?result;
???function?count(){
???????var?a=document.getElementById('txt1').value;
???????var?b=document.getElementById('txt2').value;
???????var?cu=document.getElementById('select').value;
???????switch?(cu){
???????case?"+":?result=?parseInt(a)+parseInt(b);?break;
???????case?"-":?result=?parseInt(a)-parseInt(b);break;
???????case?"*":?result=?parseInt(a)*parseInt(b);break;
???????default:result=?parseInt(a)/parseInt(b);?break;
?????
???????}
???}
???document.getElementById('fruit').value=result;
????//獲取第一個輸入框的值
	//獲取第二個輸入框的值
	//獲取選擇框的值
	//獲取通過下拉框來選擇的值來改變加減乘除的運算法則
????//設置結果輸入框的值?
????
???}
??</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()"/>?<!--通過?=?按鈕來調用創建的函數，得到結果-->?
???<input?type='text'?id='fruit'??/>???
?</body>
</html>

請問這個哪里錯了？

謝謝??！