function show( tagname, name )
{
    var el = document.getElementsByTagName( tagname );
    for ( var i = 0; i < el.length; i++ )
    {
        if ( el[i].getAttribute('name') == name )
        {
            el[i].style.display = 'inline';
        }
    }
}

function hide( tagname, name )
{
    var el = document.getElementsByTagName( tagname );
    for ( var i = 0; i < el.length; i++ )
    {
        if ( el[i].getAttribute('name') == name )
        {
            el[i].style.display = 'none';
        }
    }
}

function switchDisplay( id )
{
    var el_id = document.getElementById( id ).style.display;

    if ( el_id == 'none' )
    {
        document.getElementById( id ).style.display = 'inline';
    }
    else
    {
        document.getElementById( id ).style.display = 'none';
    }
}

function openWindow( url, name, params )
{
    window.open( url, name, params );
    return false;
}

function confirmAction( message )
{
    var check = window.confirm( message );
    if ( check == true )
    {
        return true;
    }
    return false;
}

function countChars( field_id, display_id, max )
{
    var field_string = document.getElementById( field_id ).value;

    // strip html tags, we do not want to count them.
    var regExp = /<.*?>/g;
    field_string = field_string.replace( regExp, '' );

    var chars = field_string.length;
    var chars_left = max - chars;
    var chars_string = chars_left + ' Zeichen noch zur Verf&uuml;gung';
    if ( chars_left < 0 )
    {
        chars_string = '<span style="font-weight:bold;color:darkred;">' + chars_string + '</span>';
    }
    else if ( chars_left < 20 )
    {
        chars_string = '<b>' + chars_string + '</b>';
    }
    document.getElementById( display_id ).innerHTML = chars_string;
}

function checkField( field, message )
{
    if ( field.value || isChecked( field ) )
    {
        return true;
    }
    else
    {
        alert ( message );
        return false;
    }
}

function isChecked ( field )
{
    for ( i=0; i<field.length; i++ )
    {
        if ( field[i].checked == true )
        {
            return true;
        }
    }

    return false;
}