title: How to create a call back function and store the value of the variable
body: <p>I am reading a Rss feed using setInterval method and displaying notification to the users ,I want to make sure I store the latest feed title so that the user does not get multiple notification of the same title again. The current implementation does not work because I cant use that variable until the response comes back. To make things worse I am delaying the execution.So I am guessing I need to use callback function get the value and do my checking inside that function. I am not able to figure out how to do the callback and get the value of entry_title.</p>
  
  <pre><code>/** global variable **/
  
  var global_Rsstitle;
  
  /** end global variable **/
  
  function get_rss1_feeds() {
  
      var Rss1_title = getRss("http://rss.cnn.com/rss/cnn_topstories.rss", function(entry_title) {
          if(global_Rsstitle != entry_title)
          global_Rsstitle = entry_title;
          console.log('test',global_Rsstitle); // the value is outputed but global var is not working
      });
  console.log('test1',global_Rsstitle);   // outputted as undefined ??
      }
  
      google.load("feeds", "1");
      google.setOnLoadCallback(function () { setInterval(get_rss1_feeds, 5000); });
  </code></pre>
  
  <p>My jsRss.js</p>
  
  <pre><code>function getRss(url, callback){
      if(url == null) return false;
  
      // Our callback function, for when a feed is loaded.
      function feedLoaded(result) {
          if (!result.error) {
              var entry = result.feed.entries[0];
              var entry_title = entry.title; // need to get this value
              callback &amp;&amp; callback(entry_title);        
          }
      }
      function Load() {       
          // Create a feed instance that will grab feed.
          var feed = new google.feeds.Feed(url);
          // Calling load sends the request off.  It requires a callback function.
          feed.load(feedLoaded);      
      }    
      Load();             
  }
  </code></pre>
  
  <p>can u see the entry_title -> this stores d value i need
  so i need to get this value n store it into a global variable 
  or send it to another fns as a argument 
  so that I can maintain the value 
  and when next time setInterval is fired
  I get a new value so I can compare and check if its same
  n if its same I dont display it to the user</p>