var request;

function createRequest() {
  try {
    request = new XMLHttpRequest();
		
  } catch ( trymicrosoft ) {
    try {
      request = new ActiveXObject( "Msxml2.XMLHTTP" );
			
    } catch ( othermicrosoft ) {
      try {
        request = new ActiveXObject( "Microsoft.XMLHTTP" );
				
      } catch ( failed ) {
        request = false;
				
      }
			
    }
		
  }

  if ( !request ) {
    // alert( "Error initializing XMLHttpRequest!" );
	}
}

function getHeader() {
	var header = "";
	
	if ( request ) {
		request.open( "HEAD", "images/autosnap.jpg", true );
		request.onreadystatechange = function() {
			var outputTo = document.getElementById( "divModified" );
			if ( request.readyState == 4 ) {
				if ( request.status == 200 ) {
					header = request.getResponseHeader( "Last-Modified" );
					
				} else if ( request.status == 404 ) {
					header = "404: image unavailable";
					
				} else {
					header = "Problem trying to get image header: " + request.status;
					
				}
				
			}
			
		}
		request.send( null );

	} else {
		header = "AJAX unavailable";
		
	}
	
	return header;
	
}

createRequest();