<!DOCTYPE?html>
<html>
?<head>
??<title>?事件</title>??
??<script?type="text/javascript">
???function?count(){
???????
????var?a=parseInt(document.getElementById("txt1").value);//獲取第一個輸入框的值
var?b=parseInt(document.getElementById("txt2").value);//獲取第二個輸入框的值
var?c=document.getElementById("select").value;//獲取選擇框的值
????var?result='';
switch(c)
????{
????????case1?'+':result=a+b;break;
????????case1?'-':result=a-b;break;
????????case1?'*':result=a*b;break;
????????case1?'/':result=a/b;break;
????}//獲取通過下拉框來選擇的值來改變加減乘除的運算法則
????result=document.getElementById("fruit").value;//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>
2016-03-08
<!DOCTYPE?html> <html> <head> ????<title>?事件</title> ????<script?type="text/javascript"> ????????function?count(){ ????????????var?a=parseInt(document.getElementById("txt1").value);//獲取第一個輸入框的值 ????????????var?b=parseInt(document.getElementById("txt2").value);//獲取第二個輸入框的值 ????????????var?c=document.getElementById("select").value;//獲取選擇框的值 ????????????var?result=''; ????????????switch(c) ????????????{ ????????????????case?'+':result=a+b;break; ????????????????????case?'-':result=a-b;break; ????????????????????case?'*':result=a*b;break; ????????????????????case?'/':result=a/b;break; ????????????}//獲取通過下拉框來選擇的值來改變加減乘除的運算法則 ????????????document.getElementById("fruit").value=result;//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>兩處錯誤
1、document.getElementById("fruit").value=result; ?把結果賦值給輸入框
2、case 不是 case1 ? 如case 某某： ?case '/'：
2016-03-08
result=document.getElementById("fruit").value;//設置結果輸入框的值?
=賦值的規則是：將‘='后面的值 賦給 前面的變量！
2016-03-06
?result=document.getElementById("fruit").value;//設置結果輸入框的值?
這一句代碼你把它是不是弄反了，應該是document.getElementById("fruit").value=result;