📈 Calculate a “Net Promoter Score” from an array of integers. (Array.reduce)

README.md

@flesch/net-promoter-score

Calculate a “Net Promoter Score” from an array of integers.

Install

$ npm install --save gist:34e4f906939ee1bafc74b82e64d4cc48

Usage

const nps = require('@flesch/net-promoter-score');

const score = nps([10, 9, 10, 8, 7, 5, 6, 9, 10]);

console.log(score); // => 33

_0(n)

index.js

module.exports = (ratings) => {
  const totalRatings = ratings.length;
  if (totalRatings) {
    const reduceRatings = ({ promoters, detractors }, rating) => {
      if (rating >= 0 && rating <= 10) {
        return {
          promoters: rating >= 9 ? ++promoters : promoters,
          detractors: rating <= 6 ? ++detractors : detractors,
        };
      }
      return { promoters, detractors };
    };
    const { promoters, detractors } = ratings.reduce(reduceRatings, { promoters: 0, detractors: 0 });
    return Math.round((promoters / totalRatings - detractors / totalRatings) * 100);
  }
  return 0;
};

package.json

{
  "name": "@flesch/net-promoter-score",
  "description": "Calculate a \"Net Promoter Score\" from an array of integers",
  "homepage": "https://gist.github.com/flesch/34e4f906939ee1bafc74b82e64d4cc48",
  "version": "1.0.0",
  "main": "index.js",
  "author": {
    "email": "john@fles.ch",
    "name": "John Flesch",
    "url": "https://fles.ch"
  },
  "repository": {
    "type": "git",
    "url": "git+https://gist.github.com/flesch/34e4f906939ee1bafc74b82e64d4cc48.git"
  },
  "files": ["index.js"],
  "license": "MIT"
}