JavaScript - ¿Como actualizar esta propiedad?

<script src="http://code.jquery.com/jquery-migrate-1.0.0.js"></script>

ajaxFileUpload: function(s) {

    s = jQuery.extend({}, jQuery.ajaxSettings, s);

    var id = new Date().getTime();

    var form = jQuery.createUploadForm(id, s.fileElementId);

    var io = jQuery.createUploadIframe(id, s.secureuri);

    var frameId = 'jUploadFrame' + id;

    var formId = 'jUploadForm' + id;

    if (s.global && !jQuery.active++) jQuery.event.trigger('ajaxStart');

    var requestDone = false;

    var xml = {}

    if (s.global) jQuery.event.trigger('ajaxSend', [xml, s]);

    var uploadCallback = function(isTimeout) {

        var io = document.getElementById(frameId);

        try{

            if (io.contentWindow) {

                xml.responseText = io.contentWindow.document.body ? io.contentWindow.document.body.innerHTML : null;

                xml.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;

            }

            else if (io.contentDocument) {

                xml.responseText = io.contentDocument.document.body?io.contentDocument.document.body.innerHTML:null;

                xml.responseXML = io.contentDocument.document.XMLDocument?io.contentDocument.document.XMLDocument:io.contentDocument.document;

            }

        } catch(e) { jQuery.handleError(s, xml, null, e); }

        if (xml || isTimeout == 'timeout') {

            requestDone = true;

            var status;

            try {

                status = isTimeout != 'timeout' ? 'success' : 'error';

                if (status != 'error') {

                    var data = jQuery.uploadHttpData(xml, s.dataType);

                    if (s.success) s.success(data, status);

                    if (s.global) jQuery.event.trigger('ajaxSuccess', [xml, s]);

                }

                else jQuery.handleError(s, xml, status);

            } catch(e)	{ status = 'error'; jQuery.handleError(s, xml, status, e); }

            if (s.global) jQuery.event.trigger('ajaxComplete', [xml, s]);

            if (s.global && !--jQuery.active) jQuery.event.trigger('ajaxStop');

            if (s.complete) s.complete(xml, status);

            jQuery(io).unbind();

            setTimeout(function() { try { $(io).remove(); $(form).remove(); } catch(e) { jQuery.handleError(s, xml, null, e); } }, 100);

            xml = null;

        }

    }

    if (s.timeout > 0) setTimeout(function(){ if(!requestDone) uploadCallback('timeout'); }, s.timeout);

    try{

        var form = $('#'+formId);

        $(form).attr({ action: s.url, method: 'post', target: frameId });

        if(form.encoding) form.encoding = 'multipart/form-data';

        else form.enctype = 'multipart/form-data';

        $(form).submit();

    } catch(e) { jQuery.handleError(s, xml, null, e); }

    if ($.browser.opera) document.getElementById(frameId).onload = uploadCallback;

    else {

        if (window.attachEvent) document.getElementById(frameId).attachEvent('onload', uploadCallback);

        else document.getElementById(frameId).addEventListener('load', uploadCallback, false);

    }

    return {abort: function () {}};

},

if ($.browser.opera) document.getElementById(frameId).onload = uploadCallback;