else if statement in javascript .html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Else if Statement</title>
</head>
<body>
    
    <script>
        var marks = 20;
        if(marks<= 30)
        document.write("Fail");
   else if(marks <= 40)
    document.write("C+");
 else if(marks <= 50)
document.write("B");
 else if(marks <= 60)
document.write("B+")
 else if(marks <=70)
document.write("A");
 else if(marks <= 80)
document.write("A+");
else
document.write("A++");

    </script>
</body>
</html>