JSFiddle - React, Tailwind, and code Playground

HTML

<div id="r">3121</div>
<div id="g">6334</div>
<div id="b">3445</div>
<div id="a">4121</div>

JavaScript

var    r = parseInt($('#r').text());
var    g = parseInt($('#g').text());
var    b = parseInt($('#b').text());
var    p = parseInt($('#a').text());

var mainBox = [r,g,b,a];
var minN = Math.min(r,g,b,p);
alert(minN);