I am exporting data from table convert to CSV, to JavaScript variable. . But getting Error "fputcsv() expects parameter 2 to be array" . How to do it?

This is my PHP code

<?php
require_once 'd:\xampp\htdocs\bpr\pdo_db.php';
$sql = "Select ID,FULL_NAMe,AGE from TRIAL";
$csv = get_csv_string($dbh, $sql);
echo "<script> var_csv='" . $csv . "' </script>";

function get_csv_string($dbh, $sql)
{
    try
    {
        $result = $dbh->query($sql);
        //return only the first row (we only need field names)
        $row = $result->fetch(PDO::FETCH_ASSOC);
        if ($row == null) {
            return "No Data";
        }
        $f = fopen('php://memory', 'r+');
        foreach ($row as $field => $value) {
            if (fputcsv($f, $field) === false) {
                return false;
            }
        }
        //second query gets the data
        $data = $dbh->query($sql);
        $data->setFetchMode(PDO::FETCH_ASSOC);
        foreach ($data as $row) {
            if (fputcsv($f, $row) === false) {
                return false;
            }
        } // end record loop
        rewind($f);
        $csv = stream_get_contents($f);
        return rtrim($csv);
    } catch (PDOExepction $e) {
        return $e->getMessage();
    }
    return $csv;
}

I am getting following error!

Instead of fputcsv(), I made my own code. But issue if found when I save the CSV to a javascript variable. Is there any other way to convert the data to CSV and pass it on to javascript? I will convert this csv to JSON at Client side using javascript

You're trying to output a header row to CSV with the field names.

This code fails because you're looping through the $row array and attempting to write one field header at a time.

foreach ($row as $field => $value) {
            if (fputcsv($f, $field) === false) {
                return false;
            }
        }

What you want is an array with the field names in it. You can use array_keys() for that, so your code becomes

if (fputcsv($f, array_keys($row)) === false) return false;

No loop required.