stack = 0;    
valid = 0;
function validateforumname(input) {
    stack++;

    setTimeout(
        function(input) {
            if(stack == 1) {
                check_forum_login();
              }
            stack--;
        }, 500);
    return valid;
}
function check_forum_login(thisForm) {
    if(isForumName($F('forumLogin'))) {
        var startURL = '/ajax/checkForumLogin.php';
        var params = 'forumLogin=' + $F('forumLogin');
        var ajax_auth = new Ajax.Request(startURL,
           { method:'get', 
             parameters: params,
             onSuccess: reportResp
             });
    }
    else
    {
        document.getElementById('forumLoginResult').innerHTML = "<B style=\"color:#ff0000\">Forum User Name \"" + $F('forumLogin') + "\" is invalid.</B>"
    }
    return valid;
}
function reportResp(request) {
    if (request.responseText > 0 ){
        document.getElementById('forumLoginResult').innerHTML = "<B style=\"color:#ff0000\">Forum User Name \"" + $F('forumLogin') + "\" is already in use.</B>";
        valid = 0;
    } else {
        document.getElementById('forumLoginResult').innerHTML = "";
        valid = 1;
    }
}
function isForumName( string ) {

  if (string.search(/^[A-Za-z0-9_]+$/) != -1 || string == "") return true;
  else return false;
}