<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var txt1=document.getElementById('txt1').value;
var txt2=document.getElementById('txt2').value;
var oValue=document.getElementById('select').value;
var result=0;
switch(oValue) {
case '+':
result=parseInt(txt1)+parseInt(txt2);
break;
case '-':
result=parseInt(txt1)-parseInt(txt2);
break;
case '*':
result=parseInt(txt1)*parseInt(txt2);
break;
case '/':
result=parseInt(txt1)/parseInt(txt2);
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()' /> <!--通过 = 按钮来调用创建的函数，得到结果-->
<input type='text' id='fruit' />
</body>
</html>
