A basic calculator problem. Please help

I’m a javascript beginner and I’m trying to build a simple basic calculator. But something seems to be wrong with the html or javascript file. It keeps returning only the addition(+) operator. When other buttons are clicked, nothing happens. I’ll appreciate if someone can take a look.
Thanks.

This is the link to the file.

Use querySelectorAll for selecting the buttons because you want to select all the buttons like:

const keys = document.querySelectorAll('button');

Then you can use forEach to loop over the button elements like

keys.forEach( e => {
   e.addEventListener( 'click',  event => {
                     // Do whatever you want here
         }

})

Thank you so much. It worked : )