so i am trying to create a html popup using CSS for styling and javascript for the popup motion. However, it's my first time using VS code to do it but somehow, it doesn't function.

Please help.

document.getElementById("open-popup-button");
document.addEventListener("click",function(){document.getElementsByClassName("popup")[0].classList.add("active")});

document.getElementById("dismiss-popup-button");
document.addEventListener("click",function(){document.getElementsByClassName("popup")[0].classList.remove("active")});