JSFiddle - React, Tailwind, and code Playground

HTML

<li>
    <font color="#FFFFFF">Change Background</font> 
        <ul class="dropup">
            <li><a href="#" id="140x101" onclick="changeImage(this.id)">Link 1</a></li>
            <li><a href="#" id="140x102" onclick="changeImage(this.id)">Link 2</a></li>
            <li><a href="#" id="140x103" onclick="changeImage(this.id)">Link 3</a></li>
        </ul>
</li>

CSS

body { 
    background:#000000 url('http://placehold.it/150x150') no-repeat fixed center center; 
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
}

JavaScript

function changeImage(img){
    
    document.body.style.backgroundImage = 'url(http://placehold.it/'+img+')';
    
}