<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>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<div class="searching">
<center>
<a href="javascript:void(0)" class="search-open">
<i class="fa fa-search"></i>
</a>
</center>
<div class="search-inline">
<form>
<input type="text" class="form-control" placeholder="Searching...">
<button type="submit">
<i class="fa fa-search"></i>
</button>
<a href="javascript:void(0)" class="search-close">
<i class="fa fa-times"></i>
</a>
</form>
</div>
</div>
<script>
var sp = document.querySelector('.search-open');
var searchbar = document.querySelector('.search-inline');
var shclose = document.querySelector('.search-close');
function changeClass() {
searchbar.classList.add('search-visible');
}
function closesearch() {
searchbar.classList.remove('search-visible');
}