JSFiddle - React, Tailwind, and code Playground
by wirey00
HTML
<form>
<select id="bgchanger" >
<option value="http://www.hdwallpapers.in/walls/abstract_color_background_picture_8016-wide.jpg">One</option>
<option value="http://good-wallpapers.com/wallpapers/14509/Black%20Background%20With%20Ornaments%20And%20Flourishes.jpg">Two</option>
</select>
</form>
<button onclick='changebackground(this)'>change background</button>
JavaScript
function changebackground() {
var url = document.getElementById('bgchanger').value;
document.getElementsByTagName('body')[0].style.backgroundImage = "url('" + url + "')";
}