<title></title>
<link rel="stylesheet" href="css/bootstrap.min.css" />
</head>
<body>
<div class="container" style="margin-top:50px;">
<div class="row">
<form method="get" action="https://www.baidu.com/s" id="id_form">
<div class="input-group">
<div class="input-group-btn">
<button class="btn btn-default" id="id_btn" type="submit">百度</button>
<button class="btn btn-default dropdown-toggle" data-toggle="dropdown">
<span class="caret"></span>
</button>
<ul class="dropdown-menu">
<li><a href=" ">百度</a ></li>
<li><a href="javascript:void(0)">360</a ></li>
<li><a href="javascript:void(0)">搜狗</a ></li>
</ul>
</div>
<input id="id_search" type="text" placeholder="请输入搜索内容" class="form-control" name="wd"/>
</div>
</form>
</div>
</div>
<script src="js/jquery.min.js" type="text/javascript"></script>
<script src="js/bootstrap.min.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function(){
$(".dropdown-menu li").click(function(){
let search=$(this).text();
let index=$(this).index();
$("#id_btn").text(search);
switch (index){
case 1:
$("#id_form").attr('action','https://www.so.com/s');
$("#id_search").attr('name','q');
break;
case 2:
$("#id_form").attr('action','https://www.sogou.com/web');
$("#id_search").attr('name','query');
break;
default:
break;
}
});
});