Matching Objects in Array and Consolidate

Question

UPDATE:

I have an array of objects called cars that contains li tags with attribute data about cars (such as price, car type, etc.). My goal is to consolidate these cars into one single listing if they are a match based on certain criteria.

Requirements

1. Fast Performance
2. Keep same cars array structure
3. Main Goal: Match Prepaid and Retail listings - Combine the HTML from Retail listing (such as button and pricing information) into Prepaid Listing. See:
4. If there is a match (based on criteria in IF statement), then remove the matched listing without class "listing-prepaid" AND update matched prepaid listing with certain information from retail listing.

Cars Array:

<li xmlns="http://www.w3.org/1999/xhtml" id="listing-CCAR-RM-AD-SFBT003-AD-SFBT003" data-location-id="AD-28.7455--81.2411" data-dropoff-location-id="AD-28.7455--81.2411" data-partner-name="Advantage" data-partner-code="AD" data-type="CCAR" data-vehicle-class-description="Compact Car" data-seats="5" data-bags="2" data-counter-type="ON_AIRPORT" data-prepaid="Y" data-fare-type="PREPAID" data-transmission="Automatic" data-unlimited-miles="Y" data-preferred="N" data-price="34.81" data-original-price="35.70" data-base-price="24.25" data-vehicle-example="Nissan Versa" data-highlighted="N" data-deal="Y" class="listing listing-prepaid" data-original-position="18"><div class="row"><div class="column column-images"><div class="img-wrapper"><ul class="icons"><li class="people"><span>5</span></li><li class="bags"><span>2</span></li></ul></div></div><div class="column car-details"><div class="car-title"><h3><a><span class="car-class">Compact</span><b></b></a></h3><span class="car-example">Nissan Versa or similar<sup>†</sup></span><span class="counter-type airport">Car on Airport</span></div><div class="features"><span>Unlimited Miles</span></div><div class="car-location-container"><div class="car-location"><h6>Pick-up</h6>SFB: Orlando Sanford Intl Airport</div><div class="car-location"><h6>Drop-off</h6>Same as pick-up</div></div></div><div class="column column-price"><span class="car-badge prepaid">Pay Now &amp; Save 2%</span><div class="container retail prepaid"><div class="rate"><span class="strikethrough"><span class="price-original">$25</span></span><span class="cur-symbol">$</span><span class="price">24</span><span class="rate-plan">/day</span></div><p class="button"><a class="button">Pay Now</a></p><span class="total">Total: $<span class="price">34</span></span></div></div></div><b style="clear:both;display:block;height:1px;width:1px"></b></li>

<li xmlns="http://www.w3.org/1999/xhtml" id="listing-ECAR-RP-HZ-ORLN003-HZ-ORLN003" data-location-id="HZ-28.5042--81.4284" data-dropoff-location-id="HZ-28.5042--81.4284" data-partner-name="Hertz" data-partner-code="HZ" data-type="ECAR" data-vehicle-class-description="Economy Car" data-seats="4" data-bags="1" data-counter-type="" data-prepaid="Y" data-fare-type="PREPAID" data-transmission="Automatic" data-unlimited-miles="Y" data-preferred="N" data-price="36.34" data-original-price="39.95" data-base-price="29.83" data-vehicle-example="Chevrolet Spark" data-highlighted="N" data-deal="Y" class="listing listing-prepaid" data-original-position="30"><div class="row"><div class="column column-images"><div class="img-wrapper"><ul class="icons"><li class="people"><span>4</span></li><li class="bags"><span>1</span></li></ul></div></div><div class="column car-details"><div class="car-title"><h3><a><span class="car-class">Economy</span><b></b></a></h3><span class="car-example">Chevrolet Spark or similar<sup>†</sup></span></div><div class="features"><span>Unlimited Miles</span></div><div class="car-location-container"><div class="car-location"><h6>Pick-up</h6>3575 Vineland Road, Orlando, FL</div><div class="car-location"><h6>Drop-off</h6>Same as pick-up</div></div></div><div class="column column-price"><span class="car-badge prepaid">Pay Now &amp; Save 9%</span><div class="container retail prepaid"><div class="rate"><span class="strikethrough"><span class="price-original">$33</span></span><span class="cur-symbol">$</span><span class="price">29</span><span class="rate-plan">/day</span></div><p class="button"><a class="button">Pay Now</a></p><span class="total">Total: $<span class="price">36</span></span></div></div></div><b style="clear:both;display:block;height:1px;width:1px"></b></li>

<li xmlns="http://www.w3.org/1999/xhtml" id="listing-CCAR-R-AD-SFBT003-AD-SFBT003" data-location-id="AD-28.7455--81.2411" data-dropoff-location-id="AD-28.7455--81.2411" data-partner-name="Advantage" data-partner-code="AD" data-type="CCAR" data-vehicle-class-description="Compact Car" data-seats="5" data-bags="2" data-counter-type="ON_AIRPORT" data-prepaid="N" data-fare-type="RETAIL" data-transmission="Automatic" data-unlimited-miles="Y" data-preferred="N" data-price="35.70" data-base-price="25.00" data-vehicle-example="Nissan Versa" data-highlighted="N" data-deal="N" class="listing" data-original-position="22"><div class="row"><div class="column column-images"><div class="img-wrapper"><ul class="icons"><li class="people"><span>5</span></li><li class="bags"><span>2</span></li></ul></div></div><div class="column car-details"><div class="car-title"><h3><a><span class="car-class">Compact</span><b></b></a></h3><span class="car-example">Nissan Versa or similar<sup>†</sup></span><span class="counter-type airport">Car on Airport</span></div><div class="features"><span>Free Cancellation</span><span>Pay at Pick-up</span><span>Unlimited Miles</span></div><div class="car-location-container"><div class="car-location"><h6>Pick-up</h6>SFB: Orlando Sanford Intl Airport</div><div class="car-location"><h6>Drop-off</h6>Same as pick-up</div></div></div><div class="column column-price"><div class="container retail"><div class="rate"><span class="cur-symbol">$</span><span class="price">25</span><span class="rate-plan">/day</span></div><p class="button"><a class="button">Select Car</a></p><span class="total">Total: $<span class="price">35</span></span></div></div></div><b style="clear:both;display:block;height:1px;width:1px"></b></li>

<li xmlns="http://www.w3.org/1999/xhtml" id="listing-ECAR-R-EX-MCOO001-EX-MCOO001" data-location-id="EX-28.4514095--81.3577729" data-dropoff-location-id="EX-28.4514095--81.3577729" data-partner-name="Executive" data-partner-code="EX" data-type="ECAR" data-vehicle-class-description="Economy Car" data-seats="2" data-bags="1" data-counter-type="OFF_AIR_SHTL" data-prepaid="N" data-fare-type="RETAIL" data-transmission="Automatic" data-unlimited-miles="Y" data-preferred="N" data-price="28.78" data-base-price="14.58" data-vehicle-example="SmartCar" data-highlighted="N" data-deal="N" class="listing" data-original-position="2"><div class="row"><div class="column column-images"><div class="img-wrapper"><ul class="icons"><li class="people"><span>2</span></li><li class="bags"><span>1</span></li></ul></div></div><div class="column car-details"><div class="car-title"><h3><a><span class="car-class">Economy</span><b></b></a></h3><span class="car-example">SmartCar or similar<sup>†</sup></span><span class="counter-type shuttle">Shuttle to Car</span></div><div class="features"><span>Pay at Pick-up</span><span>Unlimited Miles</span></div><div class="car-location-container"><div class="car-location"><h6>Pick-up</h6>MCO: Orlando Intl Airport</div><div class="car-location"><h6>Drop-off</h6>Same as pick-up</div></div></div><div class="column column-price"><div class="container retail"><div class="rate"><span class="cur-symbol">$</span><span class="price">14</span><span class="rate-plan">/day</span></div><p class="button"><a class="button">Select Car</a></p><span class="total">Total: $<span class="price">28</span></span></div></div></div><b style="clear:both;display:block;height:1px;width:1px"></b></li>

Expected Output:

In the above example array, the first and third listings should be a match (since they have same car type, location ids, vehicle example, etc.). The first listing should be removed from the array since it does not have class listing-prepaid AND the HTML within .column-price should be added into its prepaid match (in this example, the 3rd listing in array).

Final Product:

Code:

 cars = cars.reduce((acc, car) => {
    let retail_match = false;
    cars.forEach(car2 => {

        if (((car[0].hasAttribute("data-original-price") && car[0].getAttribute("data-original-price") === car2[0].getAttribute("data-price")) || (car2[0].hasAttribute("data-original-price") && car2[0].getAttribute("data-original-price") === car[0].getAttribute("data-price"))) && (car[0].getAttribute("data-base-price") != car2[0].getAttribute("data-base-price")) && (car[0].getAttribute("data-price") != car2[0].getAttribute("data-price")) && (car[0].getAttribute("data-type") == car2[0].getAttribute("data-type")) && (car[0].getAttribute("data-vehicle-example") == car2[0].getAttribute("data-vehicle-example")) && (car[0].getAttribute("data-location-id") == car2[0].getAttribute("data-location-id")) && (car[0].getAttribute("data-dropoff-location-id") == car2[0].getAttribute("data-dropoff-location-id")))
        {
            if (!car.hasClass("listing-prepaid"))
                retail_match = true;
            else
            {
                car.find(".column-price")
                    .addClass("prepaid-match")
                    .append(car2.find(".column-price div.retail"))
                    .find("div.retail:not(.prepaid) p.button a").text("Pay Later");
            }
        }
    });
    if (!retail_match)
        acc.push(car);
    return acc;
}, []);

Answer 1

As mentioned in the comments, using reduce keeps the complexity at O(n). This basically means, that a list twice the size will take twice the time, as the algorithm only iterates the list of cars once.

If you need to compare each item in the cars array to each other item in the cars array, the complexity with loop-like approaches will ne O(n^2), as for every additional item (roughly speaking) there will be exponentially more loops/time used.

I'm not 100% certain about the data structure of your javascript objects, but the following approach should work:

const allCars = []; // An array of cars, each item is a HTMLElement
let matchedCars = allCars.reduce((acc, car, cars) => {

   cars.forEach(car2 => {
       // For every car iterate over the cars array again to compare car to every item in the cars array (leave out this loop if you don't need the extensive comparison)

       if (car.hasAttribute("data-original-price") 
           && car2.getAttribute("data-original-price") === car.getAttribute("data-price")
          /* Add additional matching criteria here, you may access cars to get info about other cars than the current car */) {

            // Add the desired class for a match
            car.classList.add('listing-prepaid');

            // Add the matched car to the accumulator, so it ends up in the matchedCars array
            acc.push(car);
      }

   });
}, [];

An alternative approach would be to build a data structure that allows access to elements based on their attributes in a constant time (O(1)). An example would be a (Hash)Map. In this case for each element that the algorithm is looping over it is not required to loop through the whole list again to identify matches but to query the Map structure for matches.

Bonus: Given that car is a HTMLElement, you may use the dataset property to access the data-* values easier with:

car.dataset.originalPrice === car.dataset.price

Read more about this at https://developer.mozilla.org/en-US/docs/Learn/HTML/Howto/Use_data_attributes

General sources: https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement, https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce