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                        /JavaScript進階篇

哪里錯了，運行不出結(jié)果？？？？？？？？？？

<!DOCTYPE?html>
<html>
?<head>
??<title>?事件</title>??
??<script?type="text/javascript">
???function?count(){
????var?num1=parseInt(document.getElementById("text1").value);
????var?num2=parseInt(document.getElementById("text2").value);
????//獲取第一個輸入框的值
	//獲取第二個輸入框的值
	var?add=document.getElementById("select").value;
	var?result="";
	switch(add){
	????case?"+":
	????????result=?num1+num2;
	????????break;
	????case?"*":
	????????result=?num1*num2;
	????????break;
	????case?"-":
	????????result=?num1-num2;
	????????break;
	????case?"/":
	????????result=?num1/num2;
	????????break;
	}
	
	document.getElementById("fruit").value=result;
	//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(shè)置結(jié)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(diào)用創(chuàng)建的函數(shù)，得到結(jié)果-->?
???<input?type='text'?id='fruit'?/>???
?</body>
</html>