为什么出不来呀
<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var x=document.getElementById("txt1").value;
var y=document.getElementById("txt2").value;
var z=document.getElementById("select").value;
var k=document.getElementById("fruit").value;
switch(z){
case "+":
k.value=Number(x)+Number(y);
break;
case "-":
k.value=Number(x)-Number(y);
break;
case "*":
k.value=Number(x)*Number(y);
break;
case "/":
k.value=Number(x)/Number(y);
break;
}
}
</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' onclick=count() value=' = ' /> <!--通过 = 按钮来调用创建的函数，得到结果-->
<input type='text' id='fruit' />
</body>
</html>
