Javascript Regex to limit Text Field to only Numbers (Must allow non-printable keys)

Question

I have received PHP/JS code from previous developer and I need to add number validation to a Mobile Number field. I already have the HTML validation in place but I need to

Answer 1

A nice solution is described in a previous post:

jQuery('.numbersOnly').keyup(function () { 
    this.value = this.value.replace(/[^0-9\.]/g,'');
});