src/index.js
function sortMentions(mentions) {
  return mentions.slice().sort((a, b) => b.length - a.length);
}
function sortMentions(mentions) {
  return mentions.slice().sort((a, b) => b.length - a.length);
}
Sort users by username length. Longest usernames first.

@param {Array.<Object>} users
@return {Array.<Object>}