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                        /JavaScript進階篇

幫忙看看代碼哪里有錯了，不顯示結果

function count(){
??????
??? //獲取第一個輸入框的值
???? var otxt1 = document.getElementById("txt1").value;
?//獲取第二個輸入框的值
???? var otxt2 = document.getElementById("txt2").value;
?//獲取選擇框的值
??? var oselect = document.getElementById("select").value;
?//獲取通過下拉框來選擇的值來改變加減乘除的運算法則
??? var result="";
??? //設置結果輸入框的值
??? switch(select){
??? case "+";???
??? result = parseFloat(otxt1)+parseFloat(otxt2);
??? break;
??? case "-";
??? result = parseFloat(otxt1)-parseFloat(otxt2);
??? break;
??? case "*";
??? result = parseFloat(otxt1)*parseFloat(otxt2);
??? default;
??? result = parseFloat(otxt1)/parseFloat(otxt2);
??? }
??? 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 type='button' value=' = ' onclick=count() /> 
?? <input type='text' id='fruit' />??
?</body>
</html>