How to optimised this code on step 5

// 5: Create a new list item and add it to the <ul>

const list1 = document.createElement ('li');
const list1Content = document.createTextNode('This is content of new list');
const checkBox = document.createElement('input')
checkBox.setAttribute('type', 'checkbox');

list1.appendChild(checkBox);
list1.appendChild(list1Content);
ul.appendChild(list1);

// 1: Set the text of the <h1> element
const h1 = document.querySelector('h1');
h1.textContent = "This is H1 Tag"

// 2: Set the color of the <h1> to a different color
h1.style.backgroundColor = "red";

// 3: Set the content of the '.desc' paragraph
// The content should include at least one HTML tag
const desc = document.querySelector('.desc');


const p1 = document.createElement('p');
const node1 = document.createTextNode("This is what inside p1");

p1.appendChild(node1);
desc.appendChild(p1);



// 4: Set the class of the <ul> to 'list'
const ul = document.querySelector('ul');
ul.classList.add('list');


// 5: Create a new list item and add it to the <ul>

const list1 = document.createElement ('li');
const list1Content = document.createTextNode('This is content of new list');
const checkBox = document.createElement('input')
checkBox.setAttribute('type', 'checkbox');

list1.appendChild(checkBox);
list1.appendChild(list1Content);
ul.appendChild(list1);



// 6: Change all <input> elements from text fields to checkboxes

const myInput = document.querySelectorAll('input');
let i;
for (i=0; i < myInput.length; i++ ){
    myInput[i].type = 'checkbox';
}


// 7: Create a <button> element, and set its text to 'Delete'
// Add the <button> inside the '.extra' <div>
const deleteButton = document.createElement('button');
const buttonContent = document.createTextNode('Delete Area');
deleteButton.appendChild(buttonContent);

const extra = document.querySelector('.extra');
extra.appendChild(deleteButton);

// 8: Remove the '.extra' <div> element from the DOM when a user clicks the 'Delete' button

extra.addEventListener('click', () => {
    extra.remove();
});