join elements of an array of strings using a ', ' and for the last one use an ' and ', e.g., for a readable author list

happyAnd.js

const happyAnd = (strings) =>
  strings.length === 0 ? '' : strings.reduce((text, value, i, array) => 
    text + (i < array.length - 1 ? ', ' : array.length > 2 ? ', and ' : ' and ') + value);