JSFiddle - React, Tailwind, and code Playground
by jd1100
HTML
<script src="//code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<link rel="stylesheet" href="//stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css">
<script src="//stackpath.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<nav class="navbar navbar-expand-lg navbar-light bg-light">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav mr-auto">
<li class="nav-item active">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Dropdown
</a>
<div class="dropdown-menu" aria-labelledby="navbarDropdown">
<a class="dropdown-item" href="#">Action</a>
<a class="dropdown-item" href="#">Another action</a>
<div class="dropdown-divider"></div>
<a class="dropdown-item" href="#">Something else here</a>
</div>
</li>
<li class="nav-item">
<a class="nav-link disabled" href="#">Disabled</a>
</li>
</ul>
<form class="form-inline my-2 my-lg-0">
<input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
<button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
</form>
</div>
</nav>
</div>
<br><br>aaaa
CSS
.navbar {
background-color: #333;
position: fixed;
top: 0;
width: 100%;
}
.body {
overflow : auto;
}
JavaScript
$(".dropdown-toggle").on("click", function(event){//"show.bs.dropdown"
var liparent=$(this.parentElement);
var ulChild=liparent.find('ul');
var xOffset=liparent.offset().left;
var alignRight=($(document).width()-xOffset)<xOffset;
var toTop=($(document).height()-yOffset)<yOffset;
if (liparent.hasClass("dropdown-submenu"))
{
ulChild.css("left",alignRight?"-101%":"");
}
else
{
ulChild.toggleClass("dropdown-menu-right",alignRight);
}
});
$( document ).ready(function() {
var liparent=$(".dropdown");
var yOffset=liparent.offset().top;
var toTop=($(document).height()-yOffset)<yOffset;
liparent.toggleClass("dropup",toTop);
});