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                        /前端開發
                        
                            /JavaScript
                        
                        /JavaScript進階篇

為什么我的答案輸出不了？？？？

<!DOCTYPE html>
<html>
?<head>
? <title> 事件</title>?
? <script type="text/javascript">
?? function count()
?? {
??? var text_1=document.getElementById("txt1").value;
??? text_1=parseInt(text_1);
?var text_2=document.getElementById("txt2").value;
?text_2=parseInt(text_2);
?//document.write(text_2);
?var result;
?var p=document.getElementById("select").value;
?switch(p)
?{
???? case "+" :
???????? result=text_1+text_2;
???????? break;
???? case "-" :?
???????? result=text_1-text_2;
???????? break;
??? case "*" :
??????? result=text_1*text_2;
??????? break;
??? case "/" :??
???????? result=text_1/text_2;
???????? break;
???????? default;
?}
? document.getElementById("fruit").value=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 name="button" type="button" onClick="vs()" value="=" />?
?? <input type='text' id='fruit' />??
?</body>
</html>