JSFiddle - React, Tailwind, and code Playground
by Brian Dillingham
HTML
<div class="btn-group">
<button type="button" class="btn dropdown-toggle" data-toggle="dropdown">
<img src="images/flag/United-Kingdom.png" alt=""> English <span class="fa fa-bars"></span>
</button>
<ul class="dropdown-menu" role="menu">
<li><a href="#" onclick="changeDefault(this)"><img src="images/flag/Germany.png" alt="" > Deutsch</a></li>
<li><a href="#" onclick="changeDefault(this)"><img src="images/flag/France.png" alt="" > Français</a></li>
<li><a href="#" onclick="changeDefault(this)"><img src="images/flag/Spain.png" alt=""> Español</a></li>
<li><a href="#" onclick="changeDefault(this)"><img src="images/flag/Nederlands.png" alt="" > Nederlands</a></li>
</ul>
</div>
JavaScript
function changeDefault(item) {
var button = document.getElementsByClassName('dropdown-toggle')[0]
button.innerHTML = item.innerHTML + '<span class="fa fa-bars"></span>';
}