function createCookie( name, value, days )
{
    var expires;

    if ( days )
    {
        var date = new Date();
        date.setTime( date.getTime() + ( days * 24 * 60 * 60 * 1000 ) );
        expires = "; expires=" + date.toGMTString();
    }
    else
    {
        expires = "";
    }
    document.cookie = encodeURIComponent(name) + "=" + encodeURIComponent(value) + expires + "; path=/";
}

function readCookie( name )
{
    var nameEQ = encodeURIComponent(name) + "=";
    var ca = document.cookie.split( ';' );
    for (var i = 0; i < ca.length; i++)
    {
        var c = ca[ i ];
        while ( c.charAt( 0 ) === ' ' )
            c = c.substring(1, c.length);
            if ( c.indexOf( nameEQ ) === 0 )
                return decodeURIComponent( c.substring( nameEQ.length, c.length ) );
    }

    return null;
}

function eraseCookie( name )
{
    createCookie( name, "", -1 );
}