A Google Sheets function to compute ELO for Mario-Kart games

NEXT_ELO.js

var _ = LodashGS.load();

/*
NEXT_ELO Google Sheets function
 
This method computes the ELO for our Mario Kart tournament. 
 
Usage: =NEXT_ELO(results_range, elo_range)
- results_range is an horizontal range that contains the results of a game.
- elo_range is an horizontal range that contains the ELOs before that game.

Returns: an horizontal range containing the new elo of all players after 
considering the game results.

The formula is based on https://en.wikipedia.org/wiki/Elo_rating_system

Considering one results line, we consider the rank of all players that 
participated in that race, and consider wins & losses depending on other
participant's scores. If a line contains 4 players' scores, we consider
3 wins/0 losses for the first, 2w/1l for the second, 1w/2l for the third 
and 0w/3l for the fourth. There can be draws if players have the same score.

Example usage:
Sheet1:
[P1, P2, P3, P4, P5, P6]
[12, 35, 60,   , 45,   ] # You can use race or tourney points !
[12, 35, 60,   , 45,   ] 
[  ,   , 60, 22, 45, 17]
[         ...          ]

Sheet2:
[ P1  , P2  , P3  , P4  , P5  , P6   ]
[ 1000, 1000, 1000, 1000, 1000, 1000 ]
[=NEXT_ELO(Sheet1!A2:F2; Shee2!A2:F2)] ## only need to put it in the first cell !
[=NEXT_ELO(Sheet1!A3:F3; Shee2!A3:F3)]
[                 ...                ]

© Robin Nicollet
*/

function NEXT_ELO(marioKartTourneyResultsRange, currentEloLine) {
  var results = [];
  for (var i = 0; i < marioKartTourneyResultsRange[0].length; i++) {
    if (marioKartTourneyResultsRange[0][i]) {
      results.push({
        playerColumn: i,
        tourneyPoints: marioKartTourneyResultsRange[0][i],
        currentElo: currentEloLine[0][i],
      }); 
    }
  }
  
  var p = function (D) {
    return 1/(1 + Math.exp(-D / 400 * Math.LN10));
  };
  
  _.forEach(results, function (currentPlayerResult) {
    var K = 40;
    
    var currentPlayerNewElo = currentPlayerResult.currentElo;
    _.forEach(results, function (otherPlayerResult) {
      
      if (otherPlayerResult.playerColumn != currentPlayerResult.playerColumn) {
        var D = currentPlayerResult.currentElo - otherPlayerResult.currentElo;
        var W = 0;
        if (currentPlayerResult.tourneyPoints > otherPlayerResult.tourneyPoints) {
          W = 1;
        } else if (currentPlayerResult.tourneyPoints == otherPlayerResult.tourneyPoints) {
          W = 0.5;
        }
        currentPlayerNewElo += K * (W - p(D));
      }
    });
    currentPlayerResult.newElo = currentPlayerNewElo;
  });
  
  return [_.map(currentEloLine[0], function (currentElo, column) {
    var result = _.find(results, _.matches({ playerColumn: column }));
    if (result) {
      return result.newElo;
    }
    return currentElo;
  })];
}