CODE EXAMPLE FOR PHP

laravel how to nested foreach

//Laravel collection has a method that helps you group the collection. I think you can do this here.

$groupedQuarterly = $dth->mapToGroups(function ($item, $key) {
    return [$item['triwulan'] => $item];
})->toArray();

return view('Triwulan.index',compact('groupedQuarterly'));
This should yield something similar to:

[
  4 => [
    0 => [
      "id" => 2
      "kode_akun" => "bagus"
      "jenis_pajak" => "bagus"
      "nominal_pajak" => "50000"
      "npwp" => "Value"
      "nama_wp" => "Bagus"
      "ntpn" => "1234"
      "id_billing" => "123124"
      "keperluan" => "asdas"
      "bulan" => "Oktober"
      "triwulan" => "4"
      "created_at" => "2022-04-28 19:26:42"
      "updated_at" => "2022-04-28 19:26:42"
    ]
    1 => [
      "id" => 1
      ...
      "bulan" => "Nov"
      "triwulan" => "4"
      "created_at" => "2022-04-28 19:26:42"
      "updated_at" => "2022-04-28 19:26:42"
    ]
  ]
  3 => [
    0 => [
          ...
          "triwulan" => "3"
     ]
  ]
]
//where 4 and 3 indicates the "triwulan" id/number. With this I think it'd be easier for you to manipulate the views.

//and in your view:

@foreach( $$groupedQuarterly as $i => $quarter )
<div>
  Quarter {{ $i }}
  @foreach( $qurater as $month )
   <div>{{ $month["bulan"] }}</div>
  @endforeach
</div>
@endforeach