var included_files = new Array();
var infOffImg = new Image();
var infOnImg = new Image();
infOffImg.src = 'http://experimentum.ru/images/inf_off.gif';
infOnImg.src = 'http://experimentum.ru/images/inf_on.gif';

function include_once(script_filename)
{
    if (!in_array(script_filename, included_files))
    {
        included_files[included_files.length] = script_filename;
        include_dom(script_filename);
    }
}

function in_array(needle, haystack)
{
    for (var i = 0; i < haystack.length; i++)
    {
        if (haystack[i] == needle)
            return true;
    }
    return false;
}

function include_dom(script_filename)
{
    var html_doc = document.getElementsByTagName('head').item(0);
    var js = document.createElement('script');
    js.setAttribute('language', 'javascript');
    js.setAttribute('type', 'text/javascript');
    js.setAttribute('src', script_filename);
    html_doc.appendChild(js);
    return false;
}

function toggleInformers() {
    var imgs = document.getElementsByTagName('img');
    for (var i = 0; i < imgs.length; i++) {
        if (imgs[i].className == 'informer_img') {
            if (imgs[i].style.display == 'inline') {
                imgs[i].style.display = 'none';
                document.getElementById('inf_toggle_button').src = infOffImg.src;
            } else {
                imgs[i].style.display = 'inline';
                document.getElementById('inf_toggle_button').src = infOnImg.src;
            }
        }
    }
}