<!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?num1=parseInt(getElementById("txt1").value);
//獲取第二個輸入框的值
????var?num2=parseInt(getElementById("txt2").value);
//獲取選擇框的值
????var?sign=getElementById("select").value;
//獲取通過下拉框來選擇的值來改變加減乘除的運(yùn)算法則
var?result=0;
????switch(sign)
????{
????????case?"+":
????????????result=num1+num2;
????????????break;
????????case?"-":
????????????result=num1-num2;
????????????break;
????????case?"*":
????????????result=num1*num2;
????????????break;
????????case?"/":
????????????result=num1/num2;
????????????break;
????????default:
????????break;
????}
????//設(shè)置結(jié)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(diào)用創(chuàng)建的函數(shù)，得到結(jié)果-->?
???<input?type='text'?id='fruit'?/>???
?</body>
</html>
2016-11-06
改成doucument.getElementById("id") ?不能省略document對象引用，?Document對象是window對象的下一層對象，引用的語法如下：?wondow.document，window可以省略，直接對document對象進(jìn)行引用