gallery.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="./gallery.css">
    <title>Document</title>
</head>
<body>
    <div class="back">BACK</div>
    <div class="gallery-cont"></div>

    <script src="./db.js"></script>
    <script src="./gallery.js"></script>
    <script>
        let backElem = document.querySelector(".back");
        backElem.addEventListener("click", (e) => {
            location.assign("./index.html");
        })
    </script>
</body>
</html>