JSFiddle - React, Tailwind, and code Playground

HTML

<div class="sidebar-feed-container">
            <?php 
            //Part for the Ajax Request
            if(isset($_GET['update']) && isset($_GET['talentosLast']) && isset($_GET['interactivoLast'])){
              $getSideBarFeedInteractivo = mysql_query('SELECT id,type,text,date,logo,user FROM feeds WHERE type = "interactivo" AND date >' . $_GET['interactivoLast'] . 'ORDER BY date DESC LIMIT 20 ');
              $getSideBarFeedInteractivoArray = mysql_fetch_array($getSideBarFeedInteractivo);
              echo '<div class="hidden sidebar-item item-talentos" time="' . $getSideBarFeedInteractivoArray['date'] . '"' . '>';
              echo '<div class="sidebar-item-image">';
              echo '<img src="images/' . $getSideBarFeedInteractivoArray['logo'] . '"' . '/>';
              echo '</div>';
              echo '<div class="sidebar-item-content">';
              echo $getSideBarFeedInteractivoArray['user'] . '<br />';
              echo $getSideBarFeedInteractivoArray['text'];
              echo '</div>';
              echo '<div style="clear: both;"></div>';
              echo '</div>';

            }

              //Getting Feed Talentos Onload
          while ($row3 = mysql_fetch_array($getSideBarFeedTalentos)){
            echo '<div class="sidebar-item item-talentos" time="' . $row3['date'] . '"' . '>';
            echo '<div class="sidebar-item-image">';
            echo '<img src="images/' . $row3['logo'] . '"' . '/>';
            echo '</div>';
            echo '<div class="sidebar-item-content">';
            echo $row3['user'] . '<br />';
            echo $row3['text'];
            echo '</div>';
            echo '<div style="clear: both;"></div>';
            echo '</div>';
          }

               //Getting Feed Interactivo OnLoad
          while ($row4 = mysql_fetch_array($getSideBarFeedInteractivo)){
            echo '<div class="sidebar-item item-interactivo" time="' . $row4['date'] . '"' . '>';
            echo '<div...

JavaScript

//so we are gonna check the database for updates every every 3 seconds (3000 milliseconds)
setInterval(function () {

    var interactivoLast = $(".sidebar-feed-container>.item-interactivo:first-child").attr("time");
    var talentosLast = $(".sidebar-feed-container>.item-talentos:first-child").attr("time");
    
    var interactivoLast2 = $(".sidebar-feed-container>.item-interactivo")[0].attr("time");
    var update = "update"; //this var is just os that you can run the relevant php
    //alert(talentosLast);
    $.get("index.php", {
        'update': update, 'interactivoLast': interactivoLast, 'talentosLast': talentosLast } )
    .done(function( data ) {
        
        //so i will find the container of the 'sidebar-item's and then select all children
      var hiddenItems = $(data).find(".sidebar-feed-container").children(".hidden");
        
      //loop over items
      hiddenItems.each(function( index ) {
        //lets remove the hidden class here (when you use php on load hidden wont exist)
        $(this).removeClass("hidden");
        //prepend NOT append the html of each to the feed (the css will choose to display or not display items (eg. not display interactivo item when only talentos items are 
        //showing
        $(".sidebar-feed-container").prepend($(this));
      });
        
    });
},3000);