You can access the window.localStorage method

By setting data to the localStorage
localStorage.setItem('key', value );

And also getting
localStorage.getItem('key', value);

You can also save an array by passing data

// let’s say am saving an array of books with objects values 
localStorage.setItem('books',JSON.stringify(books));

let books = localStorage.getItem('books');
books = JSON.parse(books);

I hope this helps

To save an item to local storage:

localStorage.setItem(variable, 'value');

To get data from local storage:

let var = localStorage.getItem(variable);

Take a look at the documentation. It is really simple.

https://developer.mozilla.org/en-US/docs/Web/API/Window/localStorage

I have a simple to do app that creates to dos and displays them to the screen. However, I wan’t to save these to local storage so if someone leaves the page and returns, reloads the page, etc. the to do items remain.
I need to finish it until tomorrow and i’m struggling since hours to implement a localStorage 🙁
I appreciate every help. Thanks in advance.

here is my code on js.fiddle.net :

if (event.target.classList.contains('js-delete-todo')) {
    const itemKey = event.target.parentElement.dataset.key;
    todoloeschen(itemKey);
}

https://jsfiddle.net/mymyyy/haset7gc/