I want to single ajax uploader script into multiple uploader with the help of Iframe Javascript PHP
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I am using this reference 
http://www.openjs.com/articles/ajax/ajax_file_upload/response_data.php
for ajax uploader ,its working absolutely fine for single upload but i want to convert this script into multiple upload with the help of your guidance also helps are definitely appreciated..

I just want to know how do i target a multiple iframe with the using of single form. Current  script is target on a spacefic formId like this and this form contain only one input file...

**Code**

    <script type="text/javascript">
    function init() {
    	document.getElementById("file_upload_form").onsubmit=function() {
    	 document.getElementById("file_upload_form").target = "upload_target";
    	 document.getElementById("upload_target").onload = uploadDone; 
    	}
    }
    window.onload=init;
    <script>

    <form id="file_upload_form" method="post" enctype="multipart/form-data" action="http://www.appifylabs.com/web/php-upload-progress-bar/uploaderSecond/upload.php/">
    <input name="file" id="file" size="27" type="file" multiple="multiple"/><br />
    <input type="submit" name="action" value="Upload Image" /><br />
    <iframe id="upload_target" onload="uploadDone()" name="upload_target"  src="" style="width:600px;height:600px;border:1px solid #ccc;"></iframe>
    </form>



**Attempt** *didn't work*

    <script type="text/javascript">
        function init() {
        	document.getElementById("file_upload_form").onsubmit=function() {
        	     document.getElementById("file_1").target = "upload_target_1";
                 document.getElementById("file_2").target = "upload_target_2";
        	}
        }
    window.onload=init;
    <script>

**EDIT**

I don't want to use any third party uploader like **uploadify,JqueryUploader,Valum** etc only the reason for learn't