Given a string, return a string

So basically I want to return the string, with a message.

This is what I have so far, why am I getting undefined for the name back I have a series of test that run, and it's supposed to return a empty strong for the first test.

export const twoFer = (name) => {

  let saying = "One for" + name + "," + "One for me"
  let greeting = saying

  if (name === '') {
    let greeting = "One for you, One for me"
  } else {
    let greeting = "One for" + name + ",One for me"
  }


  return greeting;
};

I thought it would be useful to provide the tests as well so..

import { twoFer } from './two-fer'

describe('twoFer()', () => {
  test('no name given', () => {
    expect(twoFer()).toEqual("One for you, one for me.")
  })

  xtest('a name given', () => {
    expect(twoFer("Alice")).toEqual("One for Alice, one for me.")
  })

  xtest('another name given', () => {
    expect(twoFer("Bob")).toEqual("One for Bob, one for me.")
  })
})

EDIT Final Solution:

export const twoFer = (name = null) => {
  if (!name) {
    return "One for you, one for me."
  } else {
    return "One for " + name + "," + " one for me."
  }
};