JSFiddle - React, Tailwind, and code Playground

JavaScript

function ArrayCollection() {
    var myArray = new Array;
    return {
        empty: function () {
            myArray.splice(0, myArray.length);
        },
        add: function (myElement) {
            myArray.push(myElement);
        },
        getAll: function() {
            return myArray;
        },
        remove: function(item) {
            for(var i = 0; i < myArray.length; i++) {
                if(item == myArray[i]) {
                    return myArray.splice(i, 1);
                }
            }
            return null;
        }
    }
}
        
function usrSession(userID, cords, color) {
    this.UserID = userID;
    this.Cords = cords;
    this.Color = color;
}

var usrSessionCollection = new ArrayCollection();

usrSessionCollection.getLast = function(n) {
    var sessions = this.getAll();
    var session;
    var addedUserIDs = {};
    var uniqueSessions = [], count, userID;

    for(var i = sessions.length - 1; i >= 0, uniqueSessions.length < n; i--) {
        session = sessions[i];
        userID = session.UserID;

        if(!addedUserIDs[userID]) {
            uniqueSessions.push(session);
            addedUserIDs[userID] = true;
        }
    }

    return uniqueSessions;
}


var seedData = [
    { "usrID": "a", "usrcords": [1,100], "color": "red" },
    { "usrID": "b", "usrcords": [1,100], "color": "green" },
    { "usrID": "c", "usrcords": [1,100], "color": "blue" },
    { "usrID": "d", "usrcords": [1,100], "color": "green" },
    { "usrID": "d", "usrcords": [1,100], "color": "black" },
    { "usrID": "e", "usrcords": [1,100], "color": "white" },
    { "usrID": "c", "usrcords": [1,100], "color": "orange" },
    { "usrID": "g", "usrcords": [1,100], "color": "yellow" },
    { "usrID": "e", "usrcords": [1,100], "color": "red" },
    { "usrID": "e", "usrcords": [1,100], "color": "blue" }
];

$.each(seedData, function(index, data) {
    usrSessionCollection.add(new usrSession(data.usrID, data.usrcords ,data.color));
});
    
var sessions =...