how to make Javascript alert box display a variable from Rails controller

I have this piece of Javascript codes in my view file:

<script>
function hint() {
    var str = @user.name;
    var name = str.toLowerCase();

    alert(name);
}
</script>

I want the alert box to display the name of the user so I use the variable @user that was defined in my controller. However, when I click the button to active the alert box, nothing shows up. I also tried current_user.name, but it didn't work either. How can I display the value of a variable in the alert box?