filter.ts

function searchObjectArray(players, searchString, keys) {
  return players.filter(player => {
    return keys.some(key => {
      return getValueFromKey(player, key).toString().toLowerCase().includes(searchString);
    });
  });
}

function getValueFromKey(object, key) {
  return key.split(".").reduce((o, i) => o[i], object);
}