@nknahom/lotide/countOnly.js

Lotide is mini clone of the Lodash (https://lodash.com) library for learning JavaScript. What is Lodash? Lodash is a library that makes JavaScript easier by taking the hassle out of working with arrays, numbers, objects, strings, etc.

// allItems: an array of strings that we need to look through
// itemsToCount: an object specifying what to count
const countOnly = function (allItems, itemsToCount) {
  const results = {};

  for (const item of allItems) {
    // inside the loop,
    // increment the counter for each item:
    //   set a property with that string key to:
    //     the value that was already there (or zero if nothing there) with 1 added to it.
    // inside the loop:
    if (itemsToCount[item]) {
      if (results[item]) {
        results[item] += 1;
      } else {
        results[item] = 1;
      }
    }
  }
  console.log("results", results);
  return results;
};

module.exports = countOnly;