Insert an element at the end of a set of elements inside a shared parent

Call the append() method on the reference node, and pass in the new node as an argument.

// Create a new element
var newNode = document.createElement('li');
newNode.textContent = 'I am new here.';

// Get the reference node
var referenceNode = document.querySelector('#some-element');

// Insert the new node after the last element in the reference node
referenceNode.append(newNode);

Source

https://vanillajstoolkit.com/reference/dom-injection/element-append/