function bbcodeB(textareaId)
{
    bbcode(textareaId, "[b]", "[/b]");
}

function bbcodeI(textareaId)
{
    bbcode(textareaId, "[i]", "[/i]");
}

function bbcodeCenter(textareaId)
{
    bbcode(textareaId, "[center]", "[/center]");
}

function bbcodeUrl(textareaId)
{
    bbcode(textareaId, '[url=]', "[/url]");
}
function bbcodeQuote(textareaId)
{
    bbcode(textareaId, '[quote=""]\n', "\n[/quote]");
}
function bbcodeImg(textareaId)
{
    bbcode(textareaId, '[img]', "[/img]");
}

function bbcode(textareaId, startTag, endTag)
{
    var textarea = document.getElementById(textareaId);
    if(!textarea)
    {
        return;
    }

    if(typeof document.selection != "undefined") 
    {
        textarea.focus();
        var selection   = document.selection.createRange();
        selection.text  = startTag + selection.text + endTag;
   }
   else if(typeof textarea.selectionStart != "undefined")
   {
        var scrollPos       = textarea.scrollTop;
        var lng             = textarea.value.length;
        var startPos        = textarea.selectionStart;
        var endPos          = textarea.selectionEnd;
        var newSel          = startTag + textarea.value.substring(startPos, endPos) + endTag;
        
        textarea.value      = textarea.value.substring(0, startPos) + newSel + textarea.value.substring(endPos, lng);
        textarea.scrollTop  = scrollPos; 
    }
}