localStorage_example2.js

// create a new dbStore stack
var myStack = localStack('myLocalStack');

function onFormSubmit(){
   // push form data into local storage
   myStack.push( $('form').serializeArray() );
   // see if we can send data to the server
   checkForConnection();
}

function checkForConnection(){
   var ajax = new XMLHttpRequest();
   var target = "http://mysite.com/upload.php";
   // see if page is accessible
   ajax.open("HEAD", target, true);
   ajax.onreadystatechange = function(){
      // if status is 200 we can access the page
      if(ajax.readyState == 4 && ajax.status == 200) sendData();
   }
   ajax.send();
}

// run this function every 5 minutes to see if we obtained a connection
setInterval(checkForConnection, 5 * 60 * 1000);

function sendData(){
   var ajax = new XMLHttpRequest();
   var target = "http://mysite.com/upload.php"; 
   ajax.onreadystatechange = function(){
      if(ajax.readyState == 4){
         if(ajax.status == 200 && ajax.responseText === 'OK'){
            // request was processed successfully, continue sending
            sendData();
         }else{
            // there was a problem; put data back into local storage
            myStack.push(val);
         }
      }
   }

   // fire request
   var val;
   if(val = myStack.pop()){
      ajax.open("POST", target, true); 
      ajax.setRequestHeader("Content-type", "application/x-www-form-urlencoded");   
      ajax.setRequestHeader("Content-length", val.length);  
      ajax.setRequestHeader("Connection", "close")
      ajax.send(val);
   }
}