id.html

<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title>Id</title>
    <style>
        #box-1 {
            width: 100px;
            height: 100px;
            background-color: pink;
        }
        #box-2{
            width: 100px;
            height: 100px;
            background-color: blue;
        }
    </style>
</head>

<body>
    <div id="box-1"></div>
    <div id="box-2"></div>

    <script>
        const box1 = document.getElementById("box-1");
        console.log("box1: ", box1);
        const box2 = document.querySelector("#box-2");
        console.log("box2: ", box2);
    </script>
</body>

</html>