JSFiddle - React, Tailwind, and code Playground

HTML

<div id="r">3121</div>
<div id="g">2334</div>
<div id="b">3445</div>
<div id="a">4121</div>

JavaScript

function getMinFromArray (array_of_values) {
    return array_of_values.sort()[0];   
};

var r = parseInt($('#r').text(), 10),
    g = parseInt($('#g').text(), 10),
    b = parseInt($('#b').text(), 10),
    p = parseInt($('#a').text(), 10);

var mainBox = [r,g,b,a];
var result = getMinFromArray(mainBox);

alert(result);