Is there a regular expression that will split a string between operands like +, -, * or /
similar to the following attempt that only partially works?

Code:
<script type="text/javascript">
var strIn = '123+456-321';
var tarrN = strIn.split(/\D/);
var tarrO = strIn.split(/\+|\-|\*|\//);
alert(tarrN.join('\n')+'\n\n'+tarrO.join('\n'));
</script>
Both give the same results. They split on the numbers, but loses the operators.
I was trying for an output of:
Code:
123
456
321

+
-