Jogo dado

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8"/>
    <title></title>
</head>
<body>
<h1>JS Jogo dado</h1>
<img src="face1.png" alt="dado" id="face">
<script src="arquivo.js"></script>
</body>
</html>
var sorteio = Math.floor(Math.random()* 6 + 1);
switch(sorteio){
    case 1:
        document.getElementById("face").src="face1.png";
        break;
    case 2:
        document.getElementById("face").src="face2.png";
        break;
    case 3:
        document.getElementById("face").src="face3.png";
        break;
    case 4:
        document.getElementById("face").src="face4.png";
        break;
    case 5:
        document.getElementById("face").src="face5.png";
        break;
    case 6:
        document.getElementById("face").src="face6.png";
        break;
}