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                        /JavaScript進(jìn)階篇

請(qǐng)幫忙檢查一下這段代碼的錯(cuò)誤……

<!DOCTYPE?html>
<html>
?<head>
??<title>?事件</title>??
??<script?type="text/javascript">
???function?count(){
????var?num1?=?parseInt(document.getElementById('txt1').value);
????//獲取第一個(gè)輸入框的值
????var?num1?=?parseInt(document.getElementById('txt2').value);
//獲取第二個(gè)輸入框的值
????var?cal?=?document.getElementById('select');
//獲取選擇框的值
????var?result?=?'';
????switch?(cal)?{
????????case?'+':
????????????result?=?num1?+?num2;
????????????break;
????????case?'-':
????????????result?=?num1?-?num2;
????????????break;
????????case?'*':
????????????result?=?num1?*?num2;
????????????break;
????????case?'/':
????????????result?=?num1?/?num2;
????????????break;
????}
//獲取通過(guò)下拉框來(lái)選擇的值來(lái)改變加減乘除的運(yùn)算法則
????document.getElementById('fruit').value?=?result;
????//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(guò)?=?按鈕來(lái)調(diào)用創(chuàng)建的函數(shù)，得到結(jié)果-->?
???<input?type='text'?id='fruit'?/>???
?</body>
</html>

//請(qǐng)大家麻煩幫忙檢查一下這段代碼哪里錯(cuò)了……