How to open page at a certain position?

How can I set and get the current web page scroll position?

I have a chat with position fixed and if you decide to close it, the page reloads and goes back to top, which is annoying for users..because they have to scroll back down to the point they were at.

If I could save the current scroll position (in a hidden input) before the page reloads, I could then set it back after it reloads.. right? But please, show me how to do it because I am new to this.

function closeChat() {
    var x = document.getElementById("chatArea");

    if(x.style.display == 'block'){
        x.style.display = 'none';
    }
    
    window.location.assign("explore.php");
    return false;
}

PS: I have to assign to the same page because I am sending a parameter through the url and when the chat is closed, the parameter is still there... so that's why