.sort() not working on array ( javascript)

Question

I am attempting to merge a "fresh shipment" array with a current inventory array by first creating object to make the data more manageable. So, any same-items are added to any existing ones in inventory.

.sort runs but flat doesn't seem to do anything. I suspect there is some kind of issues related to how I made the array and messing up the indices?

function updateInventory(arr1, arr2) {
    let invObj = {}
    let updateObj = {}
    let result = []

    arr1.forEach( x => invObj[x[1]] = x[0])
    arr2.forEach( x => updateObj[x[1]] = x[0])

    for(let key in updateObj) {
        if (invObj[key]) {
            invObj[key] += updateObj[key]
        } else {
            invObj[key] = updateObj[key]
        }
    }

    result =  Object.keys(invObj).map(key=>[invObj[key],key])
    .sort((a,b)=>{
    // attempting to sort inventory alphabetically here as required by my course's test
        return a[1] - b[1]
    })

    return result
}
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"]
];

console.log(updateInventory(curInv, newInv));

If you are trying to sort strings, using subtraction is inappropriate. You should use the localeCompare method off of the strings. — Taplar
– Taplar, Commented May 14, 2020 at 21:37
Also, might I suggest sorting the keys before you build out the final result. Could make your code a little cleaner — Taplar
– Taplar, Commented May 14, 2020 at 21:38
As others have written, use localCompare to compare strings. Your sort test should read return a[1].localeCompare(b[1]); — terrymorse
– terrymorse, Commented May 14, 2020 at 21:48

Taplar · Accepted Answer · 2020-05-14 21:41:29Z

3

You should use the localeCompare method when sorting string values.

function updateInventory (arr1, arr2) {
  let invObj = {};
  let updateObj = {};
  let result = [];

  arr1.forEach(x => invObj[x[1]] = x[0]);
  arr2.forEach(x => updateObj[x[1]] = x[0]);

  for (let key in updateObj) {
    if (invObj[key]) {
      invObj[key] += updateObj[key];
    } else {
      invObj[key] = updateObj[key];
    }
  }

  result = Object.keys(invObj)
    .sort((a, b) => a.localeCompare(b))
    .map(key => [invObj[key], key]);

  return result;
}

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']
];

console.log(
  updateInventory(curInv, newInv)
);

answered May 14, 2020 at 21:41

Taplar

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Comments

Joundill · Accepted Answer · 2020-05-14 21:42:39Z

Are you looking for the array to be in the same format as your data in the first instance?

function updateInventory(arr1, arr2) {
    let invObj = {}
    let updateObj = {}
    let result = []

    arr1.forEach( x => invObj[x[1]] = x[0])
    arr2.forEach( x => updateObj[x[1]] = x[0])

    for(let key in updateObj) {
        if (invObj[key]) {
            invObj[key] += updateObj[key]
        } else {
            invObj[key] = updateObj[key]
        }
    }
    
    return invObj;
}
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"]
];

console.log(updateInventory(curInv, newInv));

Waffles · Accepted Answer · 2020-05-14 21:43:42Z

0

When sorting strings it's a little more complicated because you have to take into account capitalization as well. This is a snippet from a table I made in js, hopefully it helps. You can use localecompare as well like taplar said.

            .sort(
                function(a,b) {
                    a = a[1];
                    b = b[1];
                    if (a < b) {
                        return -1; 
                    } else if (a > b) {
                        return 1;
                    } else {
                        return 0; // Equal
                    }
                });

answered May 14, 2020 at 21:43

Waffles

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Comments

epascarello · Accepted Answer · 2020-05-14 21:44:17Z

I would make a lookup object and keep references to the array items. After I loop over the current items, I would loop over the new items. Check to see if it exists and update the count. If it does not exist add the item to the inventory.

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"]
];

// make a look up object to reference by the key
var lookup = curInv.reduce( (obj, item) => ({ ...obj, [item[1]]: item }), {})

// loop over the new inventory and add it on
newInv.forEach((item) => {
  // check to see if we have the item
  var key = item[1]
  var exisiting = lookup[key]
  // if exists add it
  if (exisiting) {
    exisiting[0] += item[0]
  } else {
    // new item
    // add to our look up table in case it repeats
    lookup[key] = item
    // add it to the inventory list
    curInv.push(item)
  }
})

console.log(curInv)

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