Question

i need to send to server 50 bytes of data and receive 200 bytes in response
without reloading a page.
How can i do it?? What is the most crossbrowser way??

Answer 1

If you don’t want to use a library, take a look at this page. Nice info to make your ajax call cross browser.

And, if the data is binary, encode it

This is a snippet copied verbatim from ajax for N00bs (I strongly suggest you to read not only that post, but all of them in that site):

function callback(serverData, serverStatus) {
  alert(serverData);
}
// Called automatically when we get data back from server
// Display an alert box with the recieved data
function ajaxRequest() {
  var AJAX = null;
  // Initialize the AJAX variable.
  if (window.XMLHttpRequest) {
    // Does this browser have an XMLHttpRequest object?
    AJAX=new XMLHttpRequest();
    // Yes -- initialize it.
  } else {
    // No, try to initialize it IE style
    AJAX=new ActiveXObject("Microsoft.XMLHTTP"); // Wheee, ActiveX, how do we format c: again?
  }
  // End setup Ajax.
  if (AJAX==null) {
    // If we couldn't initialize Ajax...
    alert("Your browser doesn't support AJAX."); // Sorry msg.
    return false
    // Return false, couldn't set up ajax
  }
  AJAX.onreadystatechange = function() {
    // When the browser has the request info..
    if (AJAX.readyState==4 || AJAX.readyState=="complete") { // see if the complete flag is set.
      callback(AJAX.responseText, AJAX.status);
      // Pass the response to our processing function
    }
    // End Ajax readystate check.
  }
  var url='http://somedomain.com/getdata.php?doc=sometext.txt'; // This is the URL we will call.
  AJAX.open("GET", url, true);
  // Open the url this object was set-up with.
  AJAX.send(null);
  // Send the request.
}