# Yahoo! UI Library

### io 3.1.1

Yahoo! UI Library > io > io-upload-iframe.js (source view)
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       /**
        * Extends the IO base class to enable file uploads, with HTML forms,
        * using an iframe as the transport medium.
        * @module io
        * @submodule io-upload-iframe
        */

        var w = Y.config.win,
            d = Y.config.doc;
       /**
        * @description Parses the POST data object and creates hidden form elements
        * for each key-value, and appends them to the HTML form object.
        * @method appendData
        * @private
        * @static
        * @param {object} f HTML form object.
        * @param {string} s The key-value POST data.
        * @return {array} e Array of created fields.
        */
        function _addData(f, s) {
            var o = [],
                m = s.split('='),
                i, l;

            for (i = 0, l = m.length - 1; i < l; i++) {
                o[i] = d.createElement('input');
                o[i].type = 'hidden';
                o[i].name = m[i].substring(m[i].lastIndexOf('&') + 1);
                o[i].value = (i + 1 === l) ? m[i + 1] : m[i + 1].substring(0, (m[i + 1].lastIndexOf('&')));
                f.appendChild(o[i]);
                Y.log('key: ' +  o[i].name + ' and value: ' + o[i].value + ' added as form data.', 'info', 'io');
            }

            return o;
        }

       /**
        * @description Removes the custom fields created to pass additional POST
        * data, along with the HTML form fields.
        * @method f
        * @private
        * @static
        * @param {object} f HTML form object.
        * @param {object} o HTML form fields created from configuration.data.
        * @return {void}
        */
        function _removeData(f, o) {
            var i, l;

            for(i = 0, l = o.length; i < l; i++){
                f.removeChild(o[i]);
            }
        }

       /**
        * @description Sets the appropriate attributes and values to the HTML
        * form, in preparation of a file upload transaction.
        * @method _setAttrs
        * @private
        * @static
        * @param {object} f HTML form object.
        * @param {object} id The Transaction ID.
        * @param {object} uri Qualified path to transaction resource.
        * @return {void}
        */
        function _setAttrs(f, id, uri) {
            var ie8 = (d.documentMode && d.documentMode === 8) ? true : false;

            f.setAttribute('action', uri);
            f.setAttribute('method', 'POST');
            f.setAttribute('target', 'ioupload' + id );
            f.setAttribute(Y.UA.ie && !ie8 ? 'encoding' : 'enctype', 'multipart/form-data');
        }

       /**
        * @description Sets the appropriate attributes and values to the HTML
        * form, in preparation of a file upload transaction.
        * @method _resetAttrs
        * @private
        * @static
        * @param {object} f HTML form object.
        * @param {object} a Object of original attributes.
        * @return {void}
        */
        function _resetAttrs(f, a){
            var p;

            for (p in a) {
                if (a.hasOwnProperty(a, p)) {
                    if (a[p]) {
                        f.setAttribute(p, f[p]);
                    }
                    else {
                        f.removeAttribute(p);
                    }
                }
            }
        }

       /**
        * @description Creates the iframe transported used in file upload
        * transactions, and binds the response event handler.
        *
        * @method _create
        * @private
        * @static
        * @param {object} o Transaction object generated by _create().
        * @param {object} c Configuration object passed to YUI.io().
        * @return {void}
        */
        function _create(o, c) {
            var i = Y.Node.create('<iframe id="ioupload' + o.id + '" name="ioupload' + o.id + '" />');
                i._node.style.position = 'absolute';
                i._node.style.top = '-1000px';
                i._node.style.left = '-1000px';

            Y.one('body').appendChild(i);
            // Bind the onload handler to the iframe to detect the file upload response.
            Y.on("load", function() { _handle(o, c) }, '#ioupload' + o.id);
        }

       /**
        * @description Bound to the iframe's Load event and processes
        * the response data.
        * @method _handle
        * @private
        * @static
        * @param {o} o The transaction object
        * @param {object} c Configuration object for the transaction.
        * @return {void}
        */
        function _handle(o, c) {
            var d = Y.one('#ioupload' + o.id).get('contentWindow.document'),
                b = d.one('body'),
                p;

            if (c.timeout) {
                _clearTimeout(o.id);
            }

            if (b) {
                // When a response Content-Type of "text/plain" is used, Firefox and Safari
                // will wrap the response string with <pre></pre>.
                p = b.query('pre:first-child');
                o.c.responseText = p ? p.get('innerHTML') : b.get('innerHTML');
                Y.log('The responseText value for transaction ' + o.id + ' is: ' + o.c.responseText + '.', 'info', 'io');
            }
            else {
                o.c.responseXML =  d._node;
                Y.log('The response for transaction ' + o.id + ' is an XML document.', 'info', 'io');
            }

            Y.io.complete(o, c);
            Y.io.end(o, c);
            // The transaction is complete, so call _destroy to remove
            // the event listener bound to the iframe transport, and then
            // destroy the iframe.
            w.setTimeout( function() { _destroy(o.id); }, 0);
        }

       /**
        * @description Starts timeout count if the configuration object
        * has a defined timeout property.
        *
        * @method _startTimeout
        * @private
        * @static
        * @param {object} o Transaction object generated by _create().
        * @param {object} c Configuration object passed to YUI.io().
        * @return {void}
        */
        function _startTimeout(o, c) {
            Y.io._timeout[o.id] = w.setTimeout(
                function() {
                    var r = { id: o.id, status: 'timeout' };

                    Y.io.complete(r, c);
                    Y.io.end(r, c);
                    Y.log('Transaction ' + o.id + ' timeout.', 'info', 'io');
                }, c.timeout);
        }

       /**
        * @description Clears the timeout interval started by _startTimeout().
        * @method _clearTimeout
        * @private
        * @static
        * @param {number} id - Transaction ID.
        * @return {void}
        */
        function _clearTimeout(id) {
            w.clearTimeout(Y.io._timeout[id]);
            delete Y.io._timeout[id];
        }

       /**
        * @description
        * @method _destroy
        * @private
        * @static
        * @param {o} o The transaction object
        * @param {object} uri Qualified path to transaction resource.
        * @param {object} c Configuration object for the transaction.
        * @return {void}
        */
        function _destroy(id) {
            Y.Event.purgeElement('#ioupload' + id, false);
            Y.one('body').removeChild(Y.one('#ioupload' + id));
            Y.log('The iframe transport for transaction ' + id + ' has been destroyed.', 'info', 'io');
        }

        Y.mix(Y.io, {
           /**
            * @description Uploads HTML form data, inclusive of files/attachments,
            * using the iframe created in _create to facilitate the transaction.
            * @method _upload
            * @private
            * @static
            * @param {o} o The transaction object
            * @param {object} uri Qualified path to transaction resource.
            * @param {object} c Configuration object for the transaction.
            * @return {void}
            */
            _upload: function(o, uri, c) {
                var f = (typeof c.form.id === 'string') ? d.getElementById(c.form.id) : c.form.id,
                    fields,
                    // Track original HTML form attribute values.
                    attr = {
                        action: f.getAttribute('action'),
                        target: f.getAttribute('target')
                    };

                _create(o, c);
                // Initialize the HTML form properties in case they are
                // not defined in the HTML form.
                _setAttrs(f, o.id, uri);
                if (c.data) {
                    fields = _addData(f, c.data);
                }

                // Start polling if a callback is present and the timeout
                // property has been defined.
                if (c.timeout) {
                    _startTimeout(o, c);
                    Y.log('Transaction timeout started for transaction ' + o.id + '.', 'info', 'io');
                }

                // Start file upload.
                f.submit();
                Y.io.start(o.id, c);
                if (c.data) {
                    _removeData(f, fields);
                }
                // Restore HTML form attributes to their original values.
                _resetAttrs(f, attr);

                return {
                    id: o.id,
                    abort: function() {
                        var r = { id: o.id, status: 'abort' };

                        if (Y.one('#ioupload' + o.id)) {
                            _destroy(o.id);
                            Y.io.complete(r, c);
                            Y.io.end(r, c);
                            Y.log('Transaction ' + o.id + ' aborted.', 'info', 'io');
                        }
                        else {
                            Y.log('Attempted to abort transaction ' + o.id + ' but transaction has completed.', 'info', 'io');
                            return false;
                        }
                    },
                    isInProgress: function() {
                        return Y.one('#ioupload' + o.id) ? true : false;
                    }
                }
            }
        });

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