Phpde bunla ilgili fonksiyonlar var ama javascript te varmı bilmiyorum.
money_format() veya number_format()

<input onChange="myFunction()" type="number" id="myText" value="0">
<button id="btn">Try it</button>
<script>
function myFunction() {
  var x = document.getElementById("myText").value;
  document.getElementById("btn").value = x;
  document.getElementById("btn").innerHTML = x + " Teklif Et";
}
</script>

veya JQuery ile şağıdaki gibi yapabilirsin.

<input type="number" id="myText" value="0">
<button id="btn">Try it</button>
<script>
$( "#myText" ).change(function() {
  var v = $("#myText").prop("value");
    
    $("#btn").text(v+" Teklif et");
    $("#btn").prop("value", v);
});
</script>

<input onChange="myFunction()" type="text" id="myText" value="Some text...">
<button id="btn">Try it</button>
<script>
function myFunction() {
  var x = document.getElementById("myText").value;
  document.getElementById("btn").value = x;
}
</script>

Elimde eski bir kod var bende bi yerden bulmuştum.Kendine göre düzenleyip kulllan.

function pagination($current_page, $total_records, $total_pages, $page_url)
{
    $pagination = '';
    if($total_pages > 0 && $total_pages != 1 && $current_page <= $total_pages){ //verify total pages and current page number
        $pagination .= '<ul>';

        $right_links    = $current_page + 3;
        $previous       = $current_page - 1; //previous link
        $next           = $current_page + 1; //next link
        $first_link     = true; //boolean var to decide our first link

        if($current_page > 1){
			$previous_link = ($previous==0)?1:$previous;
            $pagination .= '<li class="pagination"><a href="'.$page_url.'?page=1">İlk</a></li>'; //first link
            $pagination .= '<li class="pagination"><a href="'.$page_url.'?page='.$previous_link.'">Önceki</a></li>'; //previous link
                for($i = ($current_page-2); $i < $current_page; $i++){ //Create left-hand side links
                    if($i > 0){
                        $pagination .= '<li class="pagination"><a href="'.$page_url.'?page='.$i.'">'.$i.'</a></li>';
                    }
                }
            $first_link = false; //set first link to false
        }

        if($first_link){ //if current active page is first link
            $pagination .= '<li class="active pagination">'.$current_page.'</li>';
        }elseif($current_page == $total_pages){ //if it's the last active link
            $pagination .= '<li class="active pagination">'.$current_page.'</li>';
        }else{ //regular current link
            $pagination .= '<li class="active pagination">'.$current_page.'</li>';
        }

        for($i = $current_page+1; $i < $right_links ; $i++){ //create right-hand side links
            if($i<=$total_pages){
                $pagination .= '<li class="pagination"><a href="'.$page_url.'?page='.$i.'">'.$i.'</a></li>';
            }
        }
        if($current_page < $total_pages){
				$next_link = ($next > $total_pages)? $total_pages : $next;
                $pagination .= '<li class="pagination"><a href="'.$page_url.'?page='.$next_link.'">İleri</a></li>'; //next link
                $pagination .= '<li class="pagination"><a href="'.$page_url.'?page='.$total_pages.'">Son</a></li>'; //last link
        }

        $pagination .= '</ul>';
    }
    return $pagination; //return pagination links
}

parcala.length; ile sayısını öğrenebilirsin.

eğer array çok fazla dinamik değilse bu işini görür.

$html = '<?php' . PHP_EOL . PHP_EOL;
        $html .= '  $blogmenu = ['.PHP_EOL;
        foreach ($blogmenu as $key => $value) {
            $html .= "      '$key' => [".PHP_EOL;
            foreach ($value as $k => $v) {
                $html .= "          '$k' => '$v',".PHP_EOL;
            }
            $html .= "      ]".PHP_EOL;
        }
    $html .= '  ];?>';
        file_put_contents('veriler.php', $html);

$html = '<?php' . PHP_EOL . PHP_EOL;
        $html .= '$blogmenu = '. print_r($array, TRUE);
    $html .= '?>';
        file_put_contents('veriler.php', $html);

->where_in yerine ->where kullan dediğin gibi where içinde kullanılıyormuş.

FIND_IN_SET içerisinde = kullanmışım yanlışlıkla orayı , ile değiştirip denseydin.

FIND_IN_SET i join içerisinde kullansan.codeignatir ı bilmiyorum ama aklıma başka bişey gelmedi.
->join('kategoriler',"FIND_IN_SET('konular.katid,kategoriler.kategori_id')","inner")