Replace switch with a better pattern (Javascript)

I have to upgrade my app to display pages based on a users type and role properties. Currently I employ a simple switch statement to do this based on user type, e.g.

switch(type) {
  case 'a':
    return CONSTANT.ONE;

  case 'b':
    return CONSTANT.TWO;

  default:
    return null;
}

The switch just returns a constant string which dictates the view showm, but that isn't scalable as number of types , roles increases. Can anyone suggest a good pattern to use in this case. I thought a state pattern might be good but is that over the top just to return a string ?

Thanks