<!DOCTYPE?html>
<html>
?<head>
??<title>?事件</title>??
??<script?type="text/javascript">
???function?count(){
??var?txt1=parseInt(var?=?document.getElementById("txt1"）.value);??//獲取第一個(gè)輸入框的值
??var?txt2=parseInt(var?=?document.getElementById('txt2'）.value); //獲取第二個(gè)輸入框的值
??var?select=document.getElementById('select').value; //獲取選擇框的值
??var?result?=?'';
switch?(select)
{case'+':?
????????result='txt1'+'txt2';
????break;
?????case'-':
?????????result='txt1'-'txt2';
????break;
?????case'*':
?????????result='txt1'*'txt2';
????break;
?????case'/':
?????????result='txt1'/'txtx2';
????break;
???}
???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(guò)?=?按鈕來(lái)調(diào)用創(chuàng)建的函數(shù)，得到結(jié)果-->?
???<input?type='text'?id='fruit'?/>???
?</body>
</html>
2015-12-27
<!doctype?html> <!DOCTYPE?html> <html> ?<head> ??<title>?事件</title>?? ??<script?type="text/javascript"> ???function?count(){ ??var?txt1=parseInt(document.getElementById("txt1").value);??//這里txt1）?反括號(hào)錯(cuò)誤 ??var?txt2=parseInt(document.getElementById('txt2').value);??//這里txt1）?反括號(hào)錯(cuò)誤 ??var?select=document.getElementById('select').value;??? ??var?result?=?''; switch?(select) ????{case'+':? ????????result=txt1+txt2;//這里去掉單引號(hào)?因?yàn)槭亲兞?????break; ?????case'-': ?????????result=txt1-txt2;//這里去掉單引號(hào)?因?yàn)槭亲兞?????break; ?????case'*': ?????????result=txt1*txt2;//這里去掉單引號(hào)?因?yàn)槭亲兞?????break; ?????case'/': ?????????result=txt1/txt2;//這里去掉單引號(hào)?因?yàn)槭亲兞??txt2誤寫(xiě)成txtx2 ????break; ???} ???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(guò)?=?按鈕來(lái)調(diào)用創(chuàng)建的函數(shù)，得到結(jié)果-->? ???<input?type='text'?id='fruit'?/>??? ?</body> </html> //例如除數(shù)不能為零?等細(xì)節(jié)?多注意就可以了2015-12-27
??var?txt1=parseInt(document.getElementById("txt1").value);??//獲取第一個(gè)輸入框的值 ??var?txt2=parseInt(document.getElementById('txt2').value);//??")"寫(xiě)成了中文格式，去掉"var="????{case'+':? ????????result=txt1+txt2;//去掉引號(hào)，如果有引號(hào)就表示是字符串而不是變量 ????break; ?????case'-': ?????????result=txt1-txt2; ????break; ?????case'*': ?????????result=txt1*txt2; ????break; ?????case'/': ?????????result=txt1/txtx2; ????break; ???}