这是什么情况？
<!doctype html>
<html>
<head>
<meta charset="UTF-8" />
<title>Document</title>
<style type="text/css">
div {
margin-left: 5%;
width: 600px;
}
</style>
<script type="text/javascript">
function count() {
var result = 0;
var number1_1 = document.getElementById("number1").value;
var number1_2 = document.getElementById("number2").value;
var symbolC = document.getElementById("selects").value;
switch(symbolC) {
case "+":
result = number1_1 + number1_2;
break;
case "-":
result = number1_1 - number1_2;
break;
case "*":
result = number1_1 * number1_2;
break;
case "/":
result = number1_1 / number1_2;
break;
default:
break;
}
document.getElementById("result1").value=result;
}
</script>
</head>
<body>
<div>
<input type="number" id="number1" />
<select id="selects">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
</select>
<input type="number" id="number2" />
<input type="button" value="=" onclick="count()" />
<input type="text" id="result1" disabled="disabled" />
</div>
</body>
</html>
