var xmlHttp = false;

try
{
	xmlHttp = new XMLHttpRequest();
}
catch ( tryMicrosoft )
{
	try
	{
		xmlHttp = new ActiveXObject( "Msxml2.XMLHTTP" );
	}
	catch ( otherMicrosoft )
	{
		try
		{
			xmlHttp = new ActiveXObject( "Microsoft.XMLHTTP" );
		}
		catch ( failed )
		{
			xmlHttp = false;
		}
	}
}

if ( !xmlHttp )
{
	alert( "An error has occurred with creating a connection to the web site." );
}