function list(names){
  const result = [];
  for (let i = 0; i <= names.length - 1; i++) {
    //console.log(names[i].name);
    result.push(names[i].name);
result.splice(names.length - 1, 0, ', ');
  }
  result.splice(-1, 0, ' & ');

  return result.join('');

  console.log(result);
}

list([{name: 'Bart'},{name: 'Lisa'},{name: 'Maggie'},{name: 'Homer'},{name: 'Marge'}]);

//'Bart, Lisa, Maggie, Homer & Marge'