Inserts an HTML string after the end of the specified element.
Use el.insertAdjacentHTML() with a position of 'afterend' to parse htmlString and insert it after the end of el.
const insertAfter = (el, htmlString) => el.insertAdjacentHTML('afterend', htmlString);insertAfter(document.getElementById('myId'), '<p>after</p>'); // <div id="myId">...</div> <p>after</p>