what is the function of the code?

<script language="javascript">
var isIE = document.all?true:false;
var isNS = document.layers?true:false;
function onlyDigits(e) {
var _ret = true;
if (isIE) {
if ((window.event.keyCode < 46 || window.event.keyCode > 57) && window.event.keyCode != 45) {
window.event.keyCode = 0;
_ret = false;
}
}
if (isNS) {
if (e.which < 46 || e.which > 57||e.which!=45){
e.which = 0;
_ret = false;
}
}
return (_ret);
}
</script>

I guess the name says it all: it's been used to make sure one can only enter digits in an input box, like:

what about this ??

<script language=JavaScript>
var message="";
///////////////////////////////////
function clickIE() {if (document.all) {(message);return false;}}
function clickNS(e) {if
(document.layers||(document.getElementById&&!document.all)) {
if (e.which==2||e.which==3) {(message);return false;}}}
if (document.layers)
{document.captureEvents(Event.MOUSEDOWN);document. onmousedown=clickNS;}
else{document.onmouseup=clickNS;document.oncontext menu=clickIE;}

document.oncontextmenu=new Function("return false")
// -->
</script>