Misc. data transformation utility functions.

lib.js

import { promises as fs } from "fs";
import { dirname, join } from "path";
import { fileURLToPath } from "url";

// (https://stackoverflow.com/questions/46745014/alternative-for-dirname-in-node-when-using-the-experimental-modules-flag/50052194#50052194)
const __dirname = dirname(fileURLToPath(import.meta.url));

/**
 * Create a 'data object' based on JSON files.
 * @param keys
 * @param JSONDir
 * @return {Promise} The 🔑s will be the names of the files in the given directory 👆🏽 and values will be the JSON data, of course 🙄.
 * @throws Will throw error if cannot read in all data
 */
function readDataFromJSONFiles(keys, JSONDir) {
  return (
    Promise.all(
      keys
        // Strip keys from full filenames
        .map(key => key.substring(0, key.indexOf(".")))

        // Create data object by asynchronously reading the JSON data in each file.
        .map(async key => ({
          [key]: JSON.parse(await fs.readFile(`./${JSONDir}/${key}.json`))
        }))
    )
      /**
       * 'Promise.all' will have an Array from 'map' 👆🏽.
       * Each element will be a separate object.
       * From this, we 'combine' that into the data object that we need.
       */
      .then(fileContents =>
        fileContents.reduce(
          (accumulator, data) => ({ ...accumulator, ...data }),
          {}
        )
      )
      .catch(error => {
        throw error;
      })
  );
}

/**
 * Filters data by removing keys that have values that don't include some string.
 * @param {Object} o
 * @param {Object} o.data
 * @param {string} o.key
 * @param {string} o.str
 */
export function filterByStringInclusionCondition({ data, key, str } = {}) {
  return data.filter(entry => entry[key].includes(str));
}

/**
 * @param {string} dir - name of directory containing the JSON data.
 * @return {Promise|String}
 */
export async function loadJSON(dir = "JSON") {
  let keys;

  try {
    keys = await fs.readdir(join(__dirname, dir));
  } catch (error) {
    console.error(`Error reading directory, ${dir}.`, error);
  }

  try {
    return await readDataFromJSONFiles(keys, dir);
  } catch (error) {
    return `Error reading in JSON files: ${error}`;
  }
}

export function stripBackslashes(str) {
  return str.replace(/\\/g, "");
}

export function stripHTML(str) {
  return str.replace(/(<([^>]+)>)/gi, "");
}

export function stripHTMLCharacterCodes(str) {
  return str.replace(/&[A-Za-z]+(?<!&gt|&lt);/gi, "");
}

// TODO: How to curry multiple CBs?
/**
 * Update values of given 🔑s (each 'key' should be present already) in an object.
 * @param {Object} data
 * @param {Array} keys
 * @param {Function} cb - the 'update' to perform
 * @return {Object}
 */
export function updateSpecifiedKeys({ data, keys, cb } = {}) {
  return data.map(d =>
    // For every 'd', update all of the VALUES for some specified ARRAY of 🔑s...'reduce' 🔑s down to just 1 'updated object'.
    keys.reduce(
      (updatedObject, currentKey) => ({
        ...d,
        ...updatedObject,
        ...{ [currentKey]: cb(d[currentKey]) }
      }),
      {}
    )
  );
}

export function writeJSONData(data, fileName) {
  fs.writeFile(`./${fileName}.json`, JSON.stringify(data, null, 2))
    .then(() => {
      console.log("Rote file!");
    })
    .catch(error => {
      console.error(`Error riting file: ${error}`);
    });
}

Blog post explanation

This assumes that the 🔑 s exist in each data Object.