function checkLoginForm(form)
{
    var errorMessage = '';

    errorMessage += checkUserUsername();
    errorMessage += checkUserPassword();

    if (errorMessage == '')
    {
        errorMessage += checkUserPasswordsMatch();
    }

    if (errorMessage != '')
    {
        alert("Form Error:\n" + errorMessage);
        return false;
    }

    return true;
}

function checkUserUsername()
{
    var errorMessage = '';

	document.getElementById('username').value = trim(document.getElementById('username').value);
    fieldValue = document.getElementById('username').value; 
    fieldLabel = document.getElementById('usernameLabel');
    if (fieldValue == '')
    {
        errorMessage = "    - You must enter a username.\n";

        fieldLabel.style.color = '#ff0000';
    }
    else
    {
        fieldLabel.style.color = '#000';
    }

    return errorMessage;
}

function checkUserPassword()
{
    var errorMessage = '';

    fieldValue = document.getElementById('password').value;
    fieldLabel = document.getElementById('passwordLabel');
    if (fieldValue == '')
    {
        errorMessage = "    - You must enter a password.\n";

        fieldLabel.style.color = '#ff0000';
    }
    else
    {
        fieldLabel.style.color = '#000';
    }

    return errorMessage;
}