required disabled sample
HTML
<form>
<input type="text" id="req" required />
<input type="text" id="dis" disabled />
<input type="text" id="req-dis" required disabled />
</form>
<div id="console"></div>
JavaScript
var log = function(log){
$("#console").append($("<div>").text(log));
};
log("req:attr="+$("#req").attr("required"));
log("req:prop="+$("#req").prop("required"));
log("dis:attr="+$("#dis").attr("disabled"));
log("dis:prop="+$("#dis").prop("disabled"));