// Function that starts the Ajax process:
 function get_availability(viewid) {

 // Confirm that the object is usable:
 if (ajax) {

 // Call the PHP script.
 // Use the GET method.
 // Pass the username in the URL.
 ajax.open('get', 'get_availability.php?viewid=' + encodeURIComponent(viewid)+'&time='+new Date());

 // Function that handles the response:
 ajax.onreadystatechange = handle_check;

 // Send the request:
 ajax.send(null);

 } else { // Can't use Ajax!
 document.getElementById("av_table").innerHTML = '';
 }

 } // End of check_username() function.

 // Function that handles the response from the PHP script:
 function handle_check() {

 // If everything's OK:
 if ( (ajax.readyState == 4) && (ajax.status == 200) ) {

 // Assign the returned value to a document element:
 document.getElementById("av_table").innerHTML = ajax.responseText;

 }

 } // End of handle_check() function.