JSFiddle - React, Tailwind, and code Playground

JavaScript

function randColor() {
    var color = (function lol(m, s, c) {
                    return s[m.floor(m.random() * s.length)] +
                        (c && lol(m, s, c - 1));
                })(Math, '3456789ABCDEF', 4);
    return color;
}

var str = "";
for (var i = 0; i < 20; i++) {
    str += "<div style='background:#" + randColor() + "'>" + randColor() + "</div>";
}

document.getElementsByTagName('body')[0].innerHTML = str;