JSFiddle - React, Tailwind, and code Playground

HTML

<div id="el1">el1</div>
<div id="el2">el2</div>

CSS

#el1 { 
    background: #0f0;
    width: 100px; height: 100px;
    position: absolute; top: 100px; left: 100px;
}

#el2 { 
    background: #00f;
    width: 100px; height: 100px;
    position: absolute; top: 150px; left: 150px;
}

JavaScript

doElsCollide = function(el1, el2) {
    el1.offsetBottom = el1.offsetTop + el1.offsetHeight;
    el1.offsetRight = el1.offsetLeft + el1.offsetWidth;
    el2.offsetBottom = el2.offsetTop + el2.offsetHeight;
    el2.offsetRight = el2.offsetLeft + el2.offsetWidth;
    
    return !((el1.offsetBottom < el2.offsetTop) ||
             (el1.offsetTop > el2.offsetBottom) ||
             (el1.offsetRight < el2.offsetLeft) ||
             (el1.offsetLeft > el2.offsetRight))
};

var el1 = document.getElementById('el1'),
    el2 = document.getElementById('el2');

alert(doElsCollide(el1, el2));