Bitmask Permissions - Extending/Revoking permissions

Question

I have a bitmask permissions + roles set:

{
    EDIT: '1',
    DELETE: '2',
    ADD: '4',
    VIEW: '8',

}

I'm looking for the simplest way to Extend and Revoke user permissions using bitwise operations.

For example a user has 7 set as permissions allowing him to EDIT, DELETE and ADD

I want to add VIEW and ADD or 12.

What is the simplest formula to extend 7 with 12 to become 15 and vice versa?

How could I revoke a users existing permissions 12 (VIEW, ADD) to revoke (DELETE, ADD) - 6 so that it would equal 8?

Answer 1

Ok I've figured out to extend you would use the Bitwise OR (|) operator like

// Extend Permissions
var userPermissions = 7;
var addPermissions  = 12;
var newPermissions  = userPermissions | addPermissions // 7 | 12 = 15

and to revoke, you would use the Bitwise AND (&) and subtract it from the users permissions like:

// Revoke Permissions
var userPermissions    = 12;
var revokePermissions  = 6;
var newPermissions     = userPermissions - (userPermissions & revokePermissions) // 12 - (12 & 6) = 8