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 str = document.getElementById('size').innerHTML; 
var res = str.replace(/<p>/g,'<input type="checkbox" value="');
var res = res.replace(/<\/p>/g,'" id="size" name="size[]" checked />');
document.getElementById('size').innerHTML=res;
});