                        課程
                    
                        /前端開發
                        
                            /JavaScript
                        
                        /JavaScript進階篇

自己寫的，可以看看

<!DOCTYPE?html>
<html>
?<head>
??<title>?四則運算器</title>??
??<script?type="text/javascript">
???function?count(){
?????var?one=document.getElementById("txt1").value
?????var?two=document.getElementById("txt2").value0
?????var?Select=document.getElementById("select").value
?????switch?(Select)
?????{case?"+":
??????document.getElementById("fruit").value=parseInt(one)?+parseInt(two)
??????break;
?????case?"-":
?????document.getElementById("fruit").value=parseInt(one)?-parseInt(two)
?????break;
?????case?"*":
?????document.getElementById("fruit").value=parseInt(one)?*parseInt(two)
?????break;
?????case?"/":
?????document.getElementById("fruit").value=parseInt(one)?/parseInt(two)
?????break;}
?????return?document.getElementById("fruit").value
????//獲取第一個輸入框的值
??//獲取第二個輸入框的值
??//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
????//設置結果輸入框的值?
????
???}
??</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?=?按鈕來調用創建的函數，得到結果-->?
???<input?type='text'?id='fruit'?/>???
?</body>
</html>