function checkNum_onkeypress(e){
var key=(typeof event!='undefined')?window.event.keyCode:e.charCode;
if((key>47 && key<58) || key == 0)return true; else return false;
}

//on document
if(navigator.appName!= "Mozilla"){document.onkeypress=checkNum_onkeypress}
//else{document.addEventListener("keyup",checkNum_onkeypress,true)}
//END on document