var xmlHttp = null;
function ajax()
{
    if(window.ActiveXObject)
    {
        try
        {
            xmlHttp = new ActiveXObject("Msxml.XMLHTTP");
        }
        catch(e)
        {
            xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
        }
    }
    else
    {
        xmlHttp = new XMLHttpRequest();
    }
    return xmlHttp;
    
}