Question: I know i can do it with preventDefault, but i don't know where to set the preventDefault on the code...

```
let navbar = document.querySelector(".navbar");

document.querySelector("#menu-btn").onclick = () => {
    navbar.classList.toggle('active');
}

window.onscroll = () => {
    navbar.classList.remove("active");
}

let hearts = document.querySelectorAll(".icons a");

hearts.forEach(a => {
    a.addEventListener("click", ()=> {a.classList.toggle("color");} 
    )
})

```

i think it is in the hearts.forEach block but i don't know where to put it

Answer: 
By restarting, I assume you mean refreshing the page (or navigating to some other pages in the case of a hyperlink)

You need to register the preventDefault in the listener, so the below should work (notice you receive an *event* argument in the event callback:

```
hearts.forEach(a => {
    a.addEventListener("click", (event) => {
      event.preventDefault();  
      a.classList.toggle("color");
    })
})

```

[Event.preventDefault](https://developer.mozilla.org/en-US/docs/Web/API/Event/preventDefault) documentation for reference
If you are trying to prevent the click event then:

```
hearts.forEach(a => {
    a.addEventListener("click", (e) => {
      e.preventDefault()
      a.classList.toggle("color")
    } 
   )
})

```