function RefreshComp(add_id)
{
    req='/ajax.php?mode=getblock_compare&key=1';
    if (add_id) req+='&add='+add_id;
    new Ajax.Request(req,   
    {     
        method:'get',
        onSuccess: function(transport)
        {       
          document.getElementById('compare').innerHTML = transport.responseText;
        },
        onFailure: function()
        { 
          document.getElementById('compare').innerHTML='Ошибка загрузки';
        }
    });     
}
function Add2Comp(id)
{
    RefreshComp(id);
}
function ClearComp()
{
    new Ajax.Request('/ajax.php?mode=clear_comp&key=1',
    {     
        method:'get',
        onSuccess: function(transport)
        {       
          RefreshComp(0);
        },
        onFailure: function()
        { 
          RefreshComp(0);
        }
    });     
}