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                        /JavaScript進階篇

代碼哪里錯了，為什么得不到結果呢？

<!DOCTYPE?html>
<html>
?<head>
??<title>?事件</title>??
??<script?type="text/javascript">
???function?count(select){
???????var?num1=parseInt(document.getElementById("txt1").value);
???????var?select=document.getElementById("select").value;
???????var?num2=parseInt(document.getElementById("txt2").value);
???????var?result;
switch(select){
case?"*":
????result=num1*num2;
break;
case?"/":
????result=num1/num2;
break;
case?"+":
????result?=?num1+num2;
break;
case?"-":
????result?=?num1-num2;
break;
default:
result="計算錯誤"；
}
document.getElementById(?"fruit").value=parseInt(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()"/>?<!--通過?=?按鈕來調用創(chuàng)建的函數(shù)，得到結果-->?
???<input?type='text'?id='fruit'?/>???
?</body>
</html>