Analyzing two arrays of objects and identifying the variance in Javascript

Question

Analyzing two arrays of objects and identifying the variance in Javascript

I am working with two arrays of objects:

\\offers
[
{DeskUID: "B11A13", Day: 06 Jun 2020}
{DeskUID: "B11A13", Day: 07 Jun 2020}
{DeskUID: "B12B34", Day: 23 Jun 2020}
]

\\reservations
[
{DeskUID: "B11A13", Day: 06 Jun 2020, Name: "Mike"}
{DeskUID: "B12B34", Day: 23 Jun 2020, Name: "Ali"}
]

My goal is to find the available offers, which are only the offers that have not been reserved yet.

\\result
[
{DeskUID: "B11A13", Day: 07 Jun 2020}
]

Here is a solution I found on Stack Overflow related to getting the difference between two arrays of objects in JavaScript

Even after trying various solutions from the provided link, I have not been successful. The result I get is always the sum of all objects from both arrays.

function comparer(otherArray){
    return function(current){
        var reserveDay = new Date(current.Day)
           return otherArray.filter(function(other){
               var offerDay = new Date(other.Day)
                   return other.DeskUID == current.DeskUID && offerDay == reserveDay
                       }).length == 0;
                           }
                               }

var onlyInA = offers.filter(comparer(reservations));
var onlyInB = reservations.filter(comparer(offers));

result = onlyInA.concat(onlyInB);

javascript arrays json javascript-objects

Answer 1

Answer №1

If you want to condense everything into a single function, you can do so like this:

const available = offers.filter(offer => { 
  return reservations.findIndex(reservation => reservation.DeskUID === offer.DeskUID && sameDateTime(new Date(reservation.Day), new Date(offer.Day))) === -1;
});

function sameDateTime(d1, d2) {
  return (
    d1.getFullYear() === d2.getFullYear() &&
    d1.getMonth() === d2.getMonth() &&
    d1.getDate() === d2.getDate()
  );
}

console.log(available);

Here's what's happening in the code snippet...

offers.filter iterates through each element in the offers array.
reservations.findIndex checks if there is a matching reservation for the current offer by comparing unique IDs and dates.
If the result is -1, it means no reservation exists, marking the offer as available.

I used string dates for simplicity, but you can easily adjust them to Date objects. Hope this solution proves useful!

UPDATE

To facilitate date comparison, I included a helper function that compares if two dates are from the same day. For more details, refer to: how to tell if two dates are in the same day?

Answer 2

If you want to condense everything into a single function, you can do so like this:

const available = offers.filter(offer => { 
  return reservations.findIndex(reservation => reservation.DeskUID === offer.DeskUID && sameDateTime(new Date(reservation.Day), new Date(offer.Day))) === -1;
});

function sameDateTime(d1, d2) {
  return (
    d1.getFullYear() === d2.getFullYear() &&
    d1.getMonth() === d2.getMonth() &&
    d1.getDate() === d2.getDate()
  );
}

console.log(available);

Here's what's happening in the code snippet...

offers.filter iterates through each element in the offers array.
reservations.findIndex checks if there is a matching reservation for the current offer by comparing unique IDs and dates.
If the result is -1, it means no reservation exists, marking the offer as available.

I used string dates for simplicity, but you can easily adjust them to Date objects. Hope this solution proves useful!

UPDATE

To facilitate date comparison, I included a helper function that compares if two dates are from the same day. For more details, refer to: how to tell if two dates are in the same day?

Answer 3

Answer №2

To filter the reservations, you can use a Set and apply the necessary filters.

var getUniqueKey = ({ DeskUID, Day }) => [DeskUID, Day].join('|'),
    availableOffers = [{ DeskUID: "B11A13", Day: "2020-06-06" }, { DeskUID: "B11A13", Day: "2020-06-07" }, { DeskUID: "B12B34", Day: "2020-06-23" }],
    reservedDesks = [{ DeskUID: "B11A13", Day: "2020-06-06", Name: "Mike" }, { DeskUID: "B12B34", Day: "2020-06-23", Name: "Ali" }],
    reservedSet = new Set(reservedDesks.map(getUniqueKey)),
    openOffers = availableOffers.filter(o => !reservedSet.has(getUniqueKey(o)));

console.log(openOffers);

Answer 4

To filter the reservations, you can use a Set and apply the necessary filters.

var getUniqueKey = ({ DeskUID, Day }) => [DeskUID, Day].join('|'),
    availableOffers = [{ DeskUID: "B11A13", Day: "2020-06-06" }, { DeskUID: "B11A13", Day: "2020-06-07" }, { DeskUID: "B12B34", Day: "2020-06-23" }],
    reservedDesks = [{ DeskUID: "B11A13", Day: "2020-06-06", Name: "Mike" }, { DeskUID: "B12B34", Day: "2020-06-23", Name: "Ali" }],
    reservedSet = new Set(reservedDesks.map(getUniqueKey)),
    openOffers = availableOffers.filter(o => !reservedSet.has(getUniqueKey(o)));

console.log(openOffers);

Answer 5

Answer №3

To successfully filter the data, you need to include the some function inside it.

var offers = [{ DeskUID: "B11A13", Day: "2020-06-06" }, { DeskUID: "B11A13", Day: "2020-06-07" }, { DeskUID: "B12B34", Day: "2020-06-23" }];
var reservations = [{ DeskUID: "B11A13", Day: "2020-06-06", Name: "Mike" }, { DeskUID: "B12B34", Day: "2020-06-23", Name: "Ali" }];

var result = offers.filter(k=>!reservations.some(d=>d.DeskUID == k.DeskUID && d.Day==k.Day));

console.log(result);

Answer 6

To successfully filter the data, you need to include the some function inside it.

var offers = [{ DeskUID: "B11A13", Day: "2020-06-06" }, { DeskUID: "B11A13", Day: "2020-06-07" }, { DeskUID: "B12B34", Day: "2020-06-23" }];
var reservations = [{ DeskUID: "B11A13", Day: "2020-06-06", Name: "Mike" }, { DeskUID: "B12B34", Day: "2020-06-23", Name: "Ali" }];

var result = offers.filter(k=>!reservations.some(d=>d.DeskUID == k.DeskUID && d.Day==k.Day));

console.log(result);

Analyzing two arrays of objects and identifying the variance in Javascript

Answer №1

Answer №2

Answer №3

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