// A generic function for performming AJAX requests
  // It takes one argument, which is an object that contains a set of options
  // All of which are outline in the comments, below
  function ajax( options ) {
  
      // Load the options object with defaults, if no
      // values were provided by the user
      options = {
          // The type of HTTP Request
          type: options.type || "POST",
  
          // The URL the request will be made to
          url: options.url || "",
  
          // How long to wait before considering the request to be a timeout
          timeout: options.timeout || 5000,
  
          // Functions to call when the request fails, succeeds,
          // or completes (either fail or succeed)
          onComplete: options.onComplete || function(){},
          onError: options.onError || function(){},
          onSuccess: options.onSuccess || function(){},
  
          // The data type that'll be returned from the server
          // the default is simply to determine what data was returned from the
          // and act accordingly.
          data: options.data || ""
      };
  
      // Create the request object
      var xml = new XMLHttpRequest();
  
      // Open the asynchronous POST request
      xml.open("GET", "/some/url.cgi", true);
  
      // We're going to wait for a request for 5 seconds, before giving up
      var timeoutLength = 5000;
  
      // Keep track of when the request has been succesfully completed
      var requestDone = false;
  
      // Initalize a callback which will fire 5 seconds from now, cancelling
      // the request (if it has not already occurred).
      setTimeout(function(){
           requestDone = true;
      }, timeoutLength);
  
      // Watch for when the state of the document gets updated
      xml.onreadystatechange = function(){
          // Wait until the data is fully loaded,
          // and make sure that the request hasn't already timed out
          if ( xml.readyState == 4 && !requestDone ) {
  
              // Check to see if the request was successful
              if ( httpSuccess( xml ) ) {
  
                  // Execute the success callback with the data returned from the server
                  options.onSuccess( httpData( xml, options.type ) );
  
              // Otherwise, an error occurred, so execute the error callback
              } else {
                  options.onError();
              }
  
              // Call the completion callback
              options.onComplete();
  
              // Clean up after ourselves, to avoid memory leaks
              xml = null;
          }
      };
  
      // Establish the connection to the server
      xml.send();
  
      // Determine the success of the HTTP response
      function httpSuccess(r) {
          try {
              // If no server status is provided, and we're actually 
              // requesting a local file, then it was successful
              return !r.status && location.protocol == "file:" ||
  
                  // Any status in the 200 range is good
                  ( r.status >= 200 && r.status < 300 ) ||
  
                  // Successful if the document has not been modified
                  r.status == 304 ||
  
                  // Safari returns an empty status if the file has not been modified
                  navigator.userAgent.indexOf("Safari") >= 0 && typeof r.status == "undefined";
          } catch(e){}
  
          // If checking the status failed, then assume that the request failed too
          return false;
      }
  
      // Extract the correct data from the HTTP response
      function httpData(r,type) {
          // Get the content-type header
          var ct = r.getResponseHeader("content-type");
  
          // If no default type was provided, determine if some
          // form of XML was returned from the server
          var data = !type && ct && ct.indexOf("xml") >= 0;
  
          // Get the XML Document object if XML was returned from
          // the server, otherwise return the text contents returned by the server
          data = type == "xml" || data ? r.responseXML : r.responseText;
  
          // If the specified type is "script", execute the returned text
          // response as if it was JavaScript
          if ( type == "script" )
              eval.call( window, data );
  
          // Return the response data (either an XML Document or a text string)
          return data;
      }
  
  }