JSFiddle - React, Tailwind, and code Playground

HTML

// Это сниппет

$month = $_POST['month'];

$sql_query = "SELECT SUBSTRING(vihodnoy, 9, 2) as day FROM table WHERE user_id='{$uid}'";
$sql_result = mysql_query($sql_query);
while ($sql_row = mysql_fetch_assoc($sql_result)){
    $array[] = $sql_row['day'];
}
$json_data = json_encode(array_values($array));?>
[<?=implode(",",$array)?>];

JavaScript

var a = [[!snippet]];