if I want to validate the input of a , and want it to contain, for example, only numerical values, but even want to give users the possibility t
/[0-9\s]/ should be a safe whitelist to use, I believe. You do need to ensure that it checks the entire input, though; I think you mean /^[0-9\s]*$/.
Also remember, of course, that you have to validate it server-side, not just in the browser. Attackers can easily bypass JavaScript validation code.