sort names with & and commas

format-names.js

/**
list([ {name: 'Bart'}, {name: 'Lisa'}, {name: 'Maggie'} ])
// returns 'Bart, Lisa & Maggie'
**/

function list(names){
  let formatNames = '';
  
  names.map((a,b) => (b < names.length-2) ? formatNames += a.name + ', ' : ((b === names.length-2) ? (formatNames += a.name + ' & ') : (formatNames += a.name)))
  
  return formatNames;
}