Function doSubmit

static/js/jquery.form.js:502–601

()

            // take a breath so that pending repaints get some cpu time before the upload starts
            function doSubmit() {
                // make sure form attrs are set
                var t = $form.attr2('target'),
                    a = $form.attr2('action'),
                    mp = 'multipart/form-data',
                    et = $form.attr('enctype') || $form.attr('encoding') || mp;

                // update form attrs in IE friendly way
                form.setAttribute('target',id);
                if (!method || /post/i.test(method) ) {
                    form.setAttribute('method', 'POST');
                }
                if (a != s.url) {
                    form.setAttribute('action', s.url);
                }

                // ie borks in some cases when setting encoding
                if (! s.skipEncodingOverride && (!method || /post/i.test(method))) {
                    $form.attr({
                        encoding: 'multipart/form-data',
                        enctype:  'multipart/form-data'
                    });
                }

                // support timout
                if (s.timeout) {
                    timeoutHandle = setTimeout(function() { timedOut = true; cb(CLIENT_TIMEOUT_ABORT); }, s.timeout);
                }

                // look for server aborts
                function checkState() {
                    try {
                        var state = getDoc(io).readyState;
                        log('state = ' + state);
                        if (state && state.toLowerCase() == 'uninitialized') {
                            setTimeout(checkState,50);
                        }
                    }
                    catch(e) {
                        log('Server abort: ' , e, ' (', e.name, ')');
                        cb(SERVER_ABORT);
                        if (timeoutHandle) {
                            clearTimeout(timeoutHandle);
                        }
                        timeoutHandle = undefined;
                    }
                }

                // add "extra" data to form if provided in options
                var extraInputs = [];
                try {
                    if (s.extraData) {
                        for (var n in s.extraData) {
                            if (s.extraData.hasOwnProperty(n)) {
                                // if using the $.param format that allows for multiple values with the same name
                                if($.isPlainObject(s.extraData[n]) && s.extraData[n].hasOwnProperty('name') && s.extraData[n].hasOwnProperty('value')) {
                                    extraInputs.push(
                                        $('<input type="hidden" name="'+s.extraData[n].name+'">').val(s.extraData[n].value)