Upload using AJAX

Hi,
I want my image to be uploaded using AJAX,
When the page loads, my imageupload form(initially it is hidden) is shown on button click,
When i upload the image it invokes AJAX.
I used

Code:

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<input type="button">

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and the imageupload form is visible after invoking AJAX.
But i want to upload image using $_FILES array. So i need to use this

Code:

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<input type="submit">

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But after when i submit the form the page is again reloading and so imageupload form is again hided.
This is my coding
AJAX

Code:

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var http = getHTTPObject(); // We create the HTTP Object
var url = "friends_classes/upload_avatar_class.php?id=";
 
function getHTTPObject() {
  var xmlhttp;
  if(window.XMLHttpRequest){
    xmlhttp = new XMLHttpRequest();
  }
  else if (window.ActiveXObject){
    xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    if (!xmlhttp){
        xmlhttp=new ActiveXObject("Msxml2.XMLHTTP");
    } 
        }
  return xmlhttp;
}

function update_avatar() { 
                if (http.readyState == 4){
      if(http.status==200) {
          var results=http.responseText;       
                      document.getElementById('upload_avatar_result').innerHTML = results;
              }
      }
}
     
function change_avatar() { 
  var sId = document.getElementById("friends_user_avatar").value;
  http.open("POST", url + escape(sId), true);
  http.onreadystatechange = update_avatar;
  http.send(null);
}

---

PHP

Code:

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<?PHP
$image=$_FILES['friends_user_avatar']['name'];
$upload_avatar=new Upload_avatar($_GET['id'],$image);
class Upload_avatar{
        function Upload_avatar($id,$image){
                echo $id;
                echo $image;
        }
}
?>

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Apparently jQuery might be able to do it (from here):

Code:

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$('submit').addEvent( 'click', function(evt){
        // Stops the submission of the form.
        new Event(evt).stop();

        // Sends the form to the action path,
        // which is 'script.php'
        $('myForm').send();
} );

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I'll take a look at the jQuery code.