<!DOCTYPE?html>
<html>
?<head>
??<title>?事件</title>??
??<script?type="text/javascript">
???function?count(){
????//獲取第一個輸入框的值
var?txt1=parseInt(document.getElementById('txt1').value);
//獲取第二個輸入框的值
var?txt2=parseInt(document.getElementById('txt2').value);
//獲取選擇框的值
var?select=document.getElementById('select').value;
var?result='';
//獲取通過下拉框來選擇的值來改變加減乘除的運算法則
switch(select)
{
case?'+':
resutl=txt1+txt2;
break;
case?'-':
result=txt1-txt2;
break;
case?'*':
resutl?=txt1*txt2;
break;
default:
result=txt1/txt2;
break;
}
????//設置結果輸入框的值?
????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()"<!--通過?=?按鈕來調用創建的函數，得到結果-->?
???<input?type='text'?id='fruit'?/>???
?</body>
</html>
2016-12-07
其他都是正確的，好像第44行有些問題，應寫成<input type='button' value=' = ' onclick="count()" /><!--通過 = 按鈕來調用創建的函數，得到結果-->
2016-12-12
?switch(select) ????{ ????????case?'+': ????????????resutl=txt1+txt2; ????????????break; ????????case?'-': ????????????result=txt1-txt2; ????????????break; ????????case?'*': ????????????resutl?=txt1*txt2; ????????????break; ????????default: ????????????result=txt1/txt2; ????????????break; ????}你上面定義的變量是"result" ，但是你+和* 這里都是寫的resutl。 都改統一了就可以了。