teamsorter.js

// given an array of teams
let teams = teamprovider.getTeams(); // don't remember the exact function name

// Create a Map
const map = new Map();
teams.forEach((team) => {
  // get the 'key'
  const key = team.name;
  // get a collection by the 'key'
  const collection = map.get(key);
  // if the collection doesn't exist, create it
  if(!collection) {
     map.set(key, [team]);
  }else {
    // if the collection exists, add to the collection
    collection.push(team);
  }
});
// turn the map into an array of team 'groups' where the groups share the same team name
let teamGroupArr = Array.from(map);
// do stuff with the group array