What's the error in addEventListener

Question

const btn = document.getElementById("btn");
const menu = document.getElementById("menu");

btn.addEventListener("click", ()=>{
if (btn.checked == true){
menu.classList.add("active");
}else {menu.classList.remove("active");}
})

Answer 1

Use the window.onload
https://code.sololearn.com/Wv9l6lAwIYL9/?ref=app