<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
var result="";
var x1 = document.getElementById("tx1").value;
var x2 = document.getElementById("tx2").value;
var x3 = document.getElementById("select").value;
switch (x3){
case "+" :
result=parseInt(x1)+parseInt(x2);
case "-" :
result=parseInt(x1)-parseInt(x2);
case "*" :
result=parseInt(x1)*parseInt(x2);
case "/" :
result=parseInt(x1)/parseInt(x2);
}
document.getElementById("fruit").value=result;
//获取第一个输入框的值
//获取第二个输入框的值
//获取选择框的值
//获取通过下拉框来选择的值来改变加减乘除的运算法则
//设置结果输入框的值
}
</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>
