根据更新值计算新平均值

Question

我有一个可以在更新数据时激活的功能，我需要让它计算统计数据的新平均值。

这是我需要更改的代码，添加新用户后它会更新统计信息：

        if (statistic !== null && statistic !== undefined) {
          let beforeLogParticipators = statistic.totalParticipation;
          let averageEnergy = statistic.averageEnergy;
          let averageEnjoyment = statistic.averageEnjoyment;
          if (beforeLogParticipators !== 0) {
            averageEnergy = averageEnergy * beforeLogParticipators;
            averageEnjoyment = averageEnjoyment * beforeLogParticipators
          }
          let afterLogParticipators = beforeLogParticipators + 1;
          let newAverageEnergy = (averageEnergy + newLog.energy) / afterLogParticipators;
          let newAverageEnjoyment = (averageEnjoyment + newLog.enjoyment) / afterLogParticipators;
          let newAverage = (newAverageEnergy + newAverageEnjoyment) / 2;
          let numberOfTeamMembers = statistic.totalMembers;
          let participationRate = (afterLogParticipators * 100) / numberOfTeamMembers;
          let newStatisticObject = {
            totalMembers: numberOfTeamMembers,
            participationRate: participationRate,
            averageEnergy: newAverageEnergy,
            averageEnjoyment: newAverageEnjoyment,
            averageStat: newAverage,
            totalParticipation: afterLogParticipators,
          };

我已经尝试了所有我知道的东西，但是无法正常工作。

不起作用的示例：

            if (statistic !== null && statistic !== undefined) {

              let newAverageEnergy = (oldStatistic.averageEnergy + statistic.averageEnergy) / 2;
              let newAverageEnjoyment = (oldStatistic.averageEnjoyment + statistic.averageEnjoyment) / 2;
              let newAverage = (newAverageEnergy + newAverageEnjoyment) / 2;
              let newStatisticObject = {
                averageEnjoyment: newAverageEnjoyment,
                averageEnergy: newAverageEnergy,
                averageStat: newAverage,
              };