JSFiddle - React, Tailwind, and code Playground

HTML

<div class="test"><p class="product_size">Lorem Ipsum 1</p></div>
<div class="test"><p class="product_size">Lorem Ipsum 2</p></div>
<div class="test"><p class="product_size">Lorem Ipsum 3</p></div>
<div class="test"><p class="product_size">Lorem Ipsum 4</p></div>

JavaScript

let divCol = document.getElementsByClassName('test');
let arr = Array.prototype.slice.call(divCol);

for (let i = 0; i < arr.length; i++) {
    console.log(arr[i].firstChild.textContent);
}