<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<nav class="navbar navbar-expand-lg navbar-dark bg-dark">
<a href="#" class="navbar-brand">Logo</a>
<button class="navbar-toggler" data-target="#navigation" data-control="navigation" data-toggle="collapse">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navigation">
<ul class="nav navbar-nav">
<li class="nav-item active">
<a href="#" class="nav-link">Home</a>
</li>
<li class="nav-item">
<a href="#" class="nav-link">Feature</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" data-toggle="dropdown" id="preview" href="#" role="button" aria-haspopup="true" aria-expanded="false">Products</a>
<div class="dropdown-menu" aria-lableledby="preview">
<a class="dropdown-item" href="#">Product1</a>
<a class="dropdown-item" href="#">Product2</a>
<a class="dropdown-item" href="#">Product3</a>
<a class="dropdown-item" href="#">Product4</a>
</div>
</li>
<li class="nav-item">
<a href="#" class="nav-link">Service</a>
</li>
<li class="nav-item">
<a href="#" class="nav-link">Contact Us</a>
</li>
</ul>
</div>
</nav>
