How to eliminate duplicates and calculate the total number of elements?

Question

JavaScript

Here is the code that displays the element IDs.
How to exclude duplicates from it and calculate the total number of elements?

<?
$arSelect = Array('ID',"PROPERTY_OTHER_COLORS");
$arFilter = Array("IBLOCK_ID"=>8, 'SECTION_ID'=>2208,"ACTIVE_DATE"=>"Y", "ACTIVE"=>"Y", '>=CATALOG_QUANTITY' => 1);
$res_count = CIBlockElement::GetList(Array(), $arFilter, Array(), Array("nPageSize"=>50), $arSelect);
$res = CIBlockElement::GetList(Array(), $arFilter, false, Array("nPageSize"=>900), $arSelect);
while($ob = $res->GetNextElement()){ 
 $arFields = $ob->GetFields();  
print_r ($arFields[ID]);
echo "</br>";
}
?>

On the screen

40413
40413
40414
40414
40420
40422
40422
40422

From my example, you need to get 4.

Answer 1

Well, there is no such element, so there is nowhere to get the text from. Make a check

let textr = '';

if (runRo && runRo.length > 0) {
    textr = runRo.innerHTML;
}

Answer 2

$arSelect = Array('ID');
$arFilter = Array("IBLOCK_ID"=>8, 'SECTION_ID'=>2208,"ACTIVE_DATE"=>"Y", "ACTIVE"=>"Y", '>=CATALOG_QUANTITY' => 1);
$res = CIBlockElement::GetList(Array(), $arFilter, false, Array("nPageSize"=>900), $arSelect);
while($ob = $res->GetNextElement()){ 
 $arFields = $ob->GetFields();  
print_r ($arFields[ID]);
echo "</br>";