<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var oTxt1=document.getElementById("txt1").value;
var oTxt2=document.getElementById("txt2").value;
var oSelt=document.getElementById("select").value;
var result="";
switch (oSelt){
case "+":
result=parseFloat(oTxt1)+parseFloat(oTxt2);
break;
case "-":
result=parseFloat(oTxt1)-parseFloat(oTxt2);
break;
case "*";
result=parseFloat(oTxt1)*parseFloat(oTxt2);
break;
default:
result=parseFloat(oTxt1)/parseFloat(oTxt2);
}
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>
找到了，case "*";这里打了分号，应该打冒号的