Somente integer no Aspxtextbox

if( (e.htmlEvent.keyCode == 189 || e.htmlEvent.keyCode == 109) ||
(e.htmlEvent.keyCode >= 48 && e.htmlEvent.keyCode <= 57) ||
(e.htmlEvent.keyCode >= 96 && e.htmlEvent.keyCode <= 105) ) {
return true; }
else {
return _aspxPreventEvent(e.htmlEvent);
}