docs.min.js：引入官方js文件，才能显示
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
<link rel="stylesheet" href="css/bootstrap.css">
<script src="js/jquery.1.12.4.min.js"></script>
<script src="js/bootstrap.js"></script>
<script src="js/docs.min.js"></script><!-- 实现出现工具提示 和占位图片-->
<title>Bootstrap</title>
</head>
<style type="text/css">
*{
font-family: 微软雅黑;
}
</style>
<body>
<div class="container">
<div class="page-header"></div>
<div class="tooltip-demo">
<button class="btn btn-default" data-toggle="tooltip" data-placement="left" data-original-title="Tooltip on left">Tooltip on left</button>
<button class="btn btn-default" data-toggle="tooltip" data-placement="top" data-original-title="Tooltip on top">Tooltip on top</button>
<button class="btn btn-default" data-toggle="tooltip" data-placement="bottom" data-original-title="Tooltip on bottom">Tooltip on bottom</button>
<button class="btn btn-default" data-toggle="tooltip" data-placement="right" data-original-title="Tooltip on right">Tooltip on right</button>
</div>
</div>
</body>
</html>
