Number of Reviews decaying weight value to dynamically factor in number of reviews along with the average score and factor in an exponentially decaying weightDecelerationFactor

numReviewsDecayingWeightFactor.js

// averageScore: float
// numReviews: int
// weightDecelerationFactor: float (a higher weightDecelerationFactor represents lower marginal value per each additional review, a lower weightDecelerationFactor represents higher marginal value per each additional review)
function parseScoreWithNumReviewsTotalValue(averageScore, numReviews, weightDecelerationFactor) {
  let nextReviewWeight = 1; 
  let totalNumReviewsWeightFactor = 1; 
  
  // Check to ensure weightDecelerationFactor is in bounds
  if (weightDecelerationFactor <= 0.00 || weightDecelerationFactor >= 1.00) {
    console.log("please provide a valid float value between 0 and 1 for the weightDecelerationFactor");
    return false;
  }

  for (i = 0; i < numReviews; i++) { 
    // First calculates the nextReviewWeight (always decreasing towards, but never reaching, 0)
    nextReviewWeight = nextReviewWeight - (nextReviewWeight * weightDecelerationFactor); 
    // Adds this nextReviewWeight to the totalNumReviewsWeightFactor
    totalNumReviewsWeightFactor = totalNumReviewsWeightFactor + nextReviewWeight; 
    // Finally multiplies weightDecelerationFactor by one minus itself to continue descresing towards zero, this represents the decreasing marginal value of each additional review
    weightDecelerationFactor = weightDecelerationFactor * (1 - weightDecelerationFactor);
    // console.log(totalNumReviewsWeightFactor);
  } 
  
  // Multiply this final totalNumReviewsWeightFactor by the given averageScore to get the calculated totalValue
  let totalValue = totalNumReviewsWeightFactor * averageScore;

  // console.log(weightDecelerationFactor);
  console.log(totalValue.toFixed(4));
  return totalValue.toFixed(4);
}

// averageScore: 3.7, numReviews: 108, weightDecelerationFactor: .70 returns a totalValue of 20.0005
parseScoreWithNumReviewsTotalValue(3.7, 108, .70);

// averageScore: 3.7, numReviews: 108, weightDecelerationFactor: .47 returns a totalValue of 29.0963
parseScoreWithNumReviewsTotalValue(3.7, 108, .47);

// averageScore: 2.1, numReviews: 108, weightDecelerationFactor: .70 returns a totalValue of 11.3516
parseScoreWithNumReviewsTotalValue(2.1, 108, .70);

// averageScore: 3.7, numReviews: 3,746, weightDecelerationFactor: .70 returns a totalValue of 38.3583
parseScoreWithNumReviewsTotalValue(3.7, 3746, .70);

// averageScore: 4.65, numReviews: 3,746, weightDecelerationFactor: .80 returns a totalValue of 38.7206
parseScoreWithNumReviewsTotalValue(4.65, 3746, .84);