figureslibres.cc/user/plugins/admin/themes/grav/js/form-attr.polyfill.js

(function($) {
    $(function() {
        /**
         * polyfill for html5 form attr
         */

        // detect if browser supports this
        var sampleElement = $('[form]').get(0);
        var isIE11 = !(window.ActiveXObject) && "ActiveXObject" in window;
        if (sampleElement && window.HTMLFormElement && sampleElement.form instanceof HTMLFormElement && !isIE11) {
            // browser supports it, no need to fix
            return;
        }

        /**
         * Append a field to a form
         *
         */
        $.fn.appendField = function(data) {
            // for form only
            if (!this.is('form')) return;

            // wrap data
            if (!$.isArray(data) && data.name && data.value) {
                data = [data];
            }

            var $form = this;

            // attach new params
            $.each(data, function(i, item) {
                $('<input/>')
                    .attr('type', 'hidden')
                    .attr('name', item.name)
                    .val(item.value).appendTo($form);
            });

            return $form;
        };

        /**
         * Find all input fields with form attribute point to jQuery object
         *
         */
        $('form[id]').submit(function(e) {
            // serialize data
            var data = $('[form=' + this.id + ']').serializeArray();
            // append data to form
            $(this).appendField(data);
        }).each(function() {
            var form    = this,
                $fields = $('[form=' + this.id + ']');

            $fields.filter('button, input')
                .filter('[type=reset],[type=submit],[type=image],button')
                .click(function() {
                    var type = this.type.toLowerCase();
                    if (type === 'reset') {
                        // reset form
                        form.reset();
                        // for elements outside form
                        $fields.each(function() {
                            this.value = this.defaultValue;
                            this.checked = this.defaultChecked;
                        }).filter('select').each(function() {
                            $(this).find('option').each(function() {
                                this.selected = this.defaultSelected;
                            });
                        });
                    } else {
                        $(form).appendField({
                            name: this.name,
                            value: this.value
                        }).submit();
                    }
                });
        });
    });

})(jQuery);