<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<style>
#wrap {
overflow: hidden;
}
#content,
#sidebar {
background-color: #eee;
}
#sidebar {
position: relative;
float: left;
width: 44px;
}
#sidebar #btn {
position: absolute;
top: 220px;
right: -20px;
width: 20px;
height: 40px;
background: red;
}
#content {
margin-left: 80px;
}
</style>
</head>
<body>
<div id="wrap">
<div id="sidebar" style="height:500px;">固定宽度区<span id="btn">点我</span></div>
<div id="content" style="height:500px;">自适应区</div>
</div>
<script src="//cdn.bootcss.com/jquery/2.2.4/jquery.min.js"></script>
<script>
var flag = 0;
$("#btn").click(function() {
if (flag == 0) {
$("#sidebar").css("width", "130px");
$("#content").css("margin-left", "166px");
flag = 1;
} else {
$("#sidebar").css("width", "44px");
$("#content").css("margin-left", "80px");
flag = 0;
}
})
</script>
</body>
</html>