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);
}
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>}
Sort users by username length . Longest usernames first .