Sort by Rank Or Get Average Rank

sortOrGetAverageRank.js

const arr = [
  {
    name: 'Sydney',
    rank: 1392
  },
  {
    name: 'London',
    rank: 1992
  },
  {
    name: 'New York',
    rank: 1132
  }
];

const sortByRank = arr => {
  return arr.sort((a, b) => a.rank - b.rank);
};

const getAvgRank = arr => {
  const values = arr.map(one => one.rank);
  let sum = values.reduce((previous, current) => (current += previous));
  let avg = sum / values.length;
  return avg;
};

// sort by ranking
console.log('list sorted: ', sortByRank(arr));

// get average of ranking
console.log('Average rank: ', getAvgRank(arr));