Group by and calculate mean / average of properties in a Javascript array

Question

I struggled finding the solution I was looking for in other stackoverflow posts, even though I strongly feel as if it must exist. If it does, please do forward me in the rig

Answer 1

const myData = [
  { team: "GSW", pts: 120 },
  { team: "HOU", pts: 100 },
  { team: "GSW", pts: 110 },
  { team: "SAS", pts: 135 },
  { team: "HOU", pts: 102 },
  { team: "SAS", pts: 127 },
  { team: "SAS", pts: 142 },
  { team: "GSW", pts: 125 }
];

var result = myData.reduce(function (a, b) {
  var exist = -1;
  //some breaks the loop once it gets the true
  a.some((x, y) => {
    if (x.team == b.team) {
      //assigning index of existing object in array
      exist = y;
      return true;
    } else {
      return false;
    }
  });
  if (exist == -1) {
    a.push({ team: b.team, pts: b.pts, count: 1 });
  } else {
    a[exist].count += 1;
    a[exist].pts += b.pts;
  }
  return a;
}, []).map(t => {return {team: t.team, avg: t.pts/t.count, count:t.count}});


console.log(result);