Remove () and - and white spaces from phone number in Javascript

You can use String.replace() to do this. Pass it a RegExp that matches everything but digits and replace them with ''.

var number = '(123) 456-7891';
number = number.replace(/[^\d]/g, ''); 

To be on the safe side, I would recommend removing everything except + (for country codes) and digits:

result = subject.replace(/[^+\d]+/g, "");