how to elements in javascript using appendChild code example

Example 1: appendchild javascript

function createMenuItem(name) {
    let li = document.createElement('li');
    li.textContent = name;
    return li;
}
// get the ul#menu
const menu = document.querySelector('#menu');
// add menu item
menu.appendChild(createMenuItem('Home'));
menu.appendChild(createMenuItem('Services'));
menu.appendChild(createMenuItem('About Us'));

Example 2: appendchild javascript

const parent = document.createElement('div');
const child = document.createElement('p');
// Appending Node Objects
parent.append(child) // Works fine
parent.appendChild(child) // Works fine
// Appending DOMStrings
parent.append('Hello world') // Works fine
parent.appendChild('Hello world') // Throws error