function register(username, email, password, errorCallback, successCallback) {
  if(username.length >= 8 && password.length >= 8){
    User.findOne((err, result, count) =>{
      if(result){
        errorCallback({message: "USERNAME ALREADY EXISTS"});
      }
      else{
        bcrypt.genSalt(10, function(err, salt) {

          bcrypt.hash(password, salt, function(err, hash) {
              const newUser = new User({
                username: username,
                email: email,
                password: hash
              });

              newUser.save((err, result)=>{
                if (err){
                  errorCallback({message: "DOCUMENT SAVE ERROR"});
                }
                else{
                  successCallback(result);
                }
              });
          });
      });
      }
    })
  }
  else{
    errorCallback({message: "USERNAME PASSWORD TOO SHORT"})
  }
}