FreeCodeCamp (Coding Interview) - Inventory Update

Inventory Update

Compare and update the inventory stored in a 2D array against a second 2D array of a fresh delivery. Update the current existing inventory item quantities (in arr1). If an item cannot be found, add the new item and quantity into the inventory array. The returned inventory array should be in alphabetical order by item.

function updateInventory(arr1, arr2) {
  // Variable for location of product
  var index;

  // A helper method to return the index of a specified product (undefined if not found)
  var getProductIndex = function (name) {
    for (var i = 0; i < this.length; i++) {
      if (this[i][1] === name) {
        return i;
      }
    }
    return undefined;
  };

  // For each item of the new Inventory
  for (var i = 0; i < arr2.length; i++) {
    // Invoke our helper function using arr1 as this
    index = getProductIndex.call(arr1, arr2[i][1]);

    // If the item doesn't exist
    if (index === undefined) {
      // Push the entire item
      arr1.push(arr2[i]);
    } else {
      // Add the new quantity of the current item
      arr1[index][0] += arr2[i][0];
    }
  }

  // Sort alphabetically, by the product name of each item
  arr1.sort(function (a, b) {
    if (a[1] > b[1]) {
      return 1;
    }
    if (a[1] < b[1]) {
      return -1;
    }
    return 0;
  });

  return arr1;
}

// Example inventory lists
var curInv = [
  [21, "Bowling Ball"],
  [2, "Dirty Sock"],
  [1, "Hair Pin"],
  [5, "Microphone"],
];

var newInv = [
  [2, "Hair Pin"],
  [3, "Half-Eaten Apple"],
  [67, "Bowling Ball"],
  [7, "Toothpaste"],
];

updateInventory(curInv, newInv);

Firstly, it is important to check whether the item already exists in the inventory. This allows us to determine whether to increase the quantity of the existing item or add a new item to the end of the inventory array.

getProductIndex() serves as our helper method for locating the index. If a match is found, the function immediately returns the index 1. If no match is found after iterating through all the elements, the function returns undefined

arr1 is invoked as this