JSFiddle - React, Tailwind, and code Playground

HTML

<div id="size">
    <p>xs</p>
    <p>s</p>
    <p>m</p>
    <p>l</p>
    <p>xl</p>
</div>

JavaScript

$(document).ready(function() {
        var list = document.getElementById('size').getElementsByTagName('p'), output = '';
        for(var i = 0; i < list.length; ++i){
            output += '<input type="checkbox" value="';
            output += list[i].innerHTML;
            output += '" id="size" name="size[]" checked />';
        }
        document.getElementById('size').innerHTML=output;
    });