JSFiddle - React, Tailwind, and code Playground

HTML

<div class="squares">
    <div id="square-1" class="square"></div>
    <div id="square-2" class="square"></div>
    <div id="square-3" class="square"></div>
    <div id="square-4" class="square"></div>
    <div id="square-5" class="square"></div>
</div>

CSS

.square {
    width: 64px;
    height: 64px;
    background: #000;
}

JavaScript

var amountToGrab = 3;

var elements = document.getElementsByClassName("square");

var ids = [];

for (var i = 0; i < elements.length; ++i)
{
    ids.push(elements[i].getAttribute("id"));
}

for (var i = 0; i < amountToGrab; ++i)
{
    var random = Math.floor(Math.random() * ids.length);
    var elementID = ids.splice(random, 1);
    
    document.getElementById(elementID).style.background = "red";
}