In IE10 in compatibility to IE8
element.attributes["required"] is null if the required attribute is missing
In IE10 in compatibility to IE7
element.attributes["required"].value returns "-1" if required attribute exists and "null" otherwise
so updated my fork to the jQuery validate plugin for this fix all details here https://github.com/avipinto/jquery-validation/commit/a22d4c37c3047199bf17a4943e3be352d88d8158