random number in javascript

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <title>random number generator</title>

    <meta name="description" content="Kovács Csaba">
    <meta name="author" content="Kovács Csaba">
</head>
<body>

<button onclick="myFunction()">Click me</button>


<p id="demo"></p>

<script>


var x = 0;
    document.getElementById("demo").innerHTML = x;


function myFunction() {
    var y = Math.floor(0 + Math.random() * 7)

    if( (x+y)>7 ){
        x=y;
    } else {
        x += y;
    }

    document.getElementById("demo").innerHTML = x;

    setTimeout(myFunction, 250);
}


</script>

</body>
</html>