Edit in JSFiddle

function mainMenuItems()
{
    browserKontrol();    
    xmlDoc=LoadXML("/upload/xml/mainmenu.xml");
    x=xmlDoc.getElementsByTagName('tab');    
    document.write('<div class="myMenu">');
       for (i=0;i<x.length;i++)
         { 
             // Sorun burada oluşuyor
         menu=x[i].childNodes[(0*(b+1))+b].childNodes[0].nodeValue;
             // Sorun burada oluşuyor
         name=x[i].childNodes[(1*(b+1))+b].childNodes[0].nodeValue;
                     document.write('<div class="buton_Sekil">');
                    document.write("<div class=");
                    document.write('"rootVoice {menu:'); 
                    document.write("'"+menu+"'}");
                    document.write('">');
                    document.write(name+"</div>");
                    document.write("</div>");
    }    
 
}