Why are these codes not working?

I have been trying to add a class with classList.add but it's not working and not throwing any error.

Comments

[Paweł Kowalski]

You have classListName, not classList.
Also you are trying to do something with buttons, not specific button in a loop.

BTW. Next time try pasting code, not image of code. Ideally in a form of jsbin/jsfiddle/codepen.

[Adedams]

Oh sorry about the presentation. This is actually my first post.

let buttons = document.querySelectorAll('button');

function display() {
buttons.forEach(buttons => {
buttons.addEventListener('click', () => {
buttons.classList.add('active')
});
})
}

[Paweł Kowalski]

Sure thing, here you have working minimal example :)

codepen.io/pavelloz/pen/YzZXzXR?ed...

I dont think you need display function at all, but since you do, you need to execute it, so evrything inside (including attaching event listeners) occur.