var $ = function(id) {
    return document.getElementById(id);
};
var checkUsername = function(username) {
    //return /^[a-zA-Z\d\.\@\-_]+$/.test(username);
    var pos = username.indexOf("@");
    if(pos == -1)
        return username.length > 0;
    else{
        var ssn = username.substring(0,pos);
        return ssn.length > 0;
    }
};