<!DOCTYPE html>
<html>
<head>
<title> 事件</title>
<script type="text/javascript">
function count(){
//获取第一个输入框的值
var num1 = parseInt(document.getElementById('txt1').value);
//获取第二个输入框的值
var num2 = parseInt(document.getElementById('txt2').value);
//获取选择框的值
var obj = document.getElementById('select');
var index = obj.selectedIndex;
switch(index){
case 0:
result = num1 + num2;
break;
case 1:
result = num1 - num2;
break;
case 2:
result = num1 * num2;
break;
case 3:
if(num2==0)alert('除数不能为0');else{
result = num1 / num2;
break; }
default:
}
//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
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' />
<br>
<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>
sissifly
2014-09-27
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