SOURCE

const data = [
  { key: 'vvq', count: 999 }, 
  { key: 'abc', count: 99 }, 
  { key: 'ww', count: 1 }, 
  { key: 'abd', count: 100 },
  { key: 'ab', count: 10 }, 
  { key: 'cs', count: 100 }, 
  { key: 'abee', count: 999 }, 
  { key: 'a', count: 11 }
];

const sortData = _.sortBy(data, 'key');

const prefixMatch = str => {
  const match = new RegExp(`^${str}`);
  const firstMatchIndex = _.findIndex(sortData, item => match.test(item.key), 0);
  let lastMatchIndex = _.findIndex(sortData, item => !match.test(item.key), firstMatchIndex);
  lastMatchIndex = lastMatchIndex === -1 ? sortData.length : lastMatchIndex;
  const filters = sortData.slice(firstMatchIndex, lastMatchIndex);
  return _.orderBy(filters, [ 'key.length', 'count' ], [ 'asc', 'desc' ]);
};

console.log(prefixMatch('ab').map(item => item.key))