Excel file is not downloading automatically via browser

Question

Basically, I am coding in Wordpress, created a function that just shows Hello World and download automatically on the browser but doesnt seem to work?

Inside: Functions.php

    wp_enqueue_script('llc-quote-profile-autocomplete', get_template_directory_uri() . '/llc-quote-profile-autocomplete.js', array('jquery', 'jquery-ui-autocomplete'), null, true);
    wp_localize_script('llc-quote-profile-autocomplete', 'llcQuoteAutocomplete', array(
        'ajaxurl' => admin_url('admin-ajax.php'),
        'nonce'   => wp_create_nonce('llc_quote_profile_autocomplete_nonce'),
    ));

require_once(ABSPATH . 'vendor/autoload.php');
use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheet\Writer\Xlsx;

function export_data_to_excel() {
    $spreadsheet = new PhpOffice\PhpSpreadsheet\Spreadsheet();
    $activeWorksheet = $spreadsheet->getActiveSheet();

    $activeWorksheet->setCellValue('A1', 'Hello World !');

    $writer = new PhpOffice\PhpSpreadsheet\Writer\Xlsx($spreadsheet);

    header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
    header('Content-Disposition: attachment; filename="hello_world.xlsx"');
    header('Cache-Control: max-age=0');

    $writer->save('php://output');

    exit;
}
add_action('wp_ajax_export_data_to_excel', 'export_data_to_excel');
add_action('wp_ajax_nopriv_export_data_to_excel', 'export_data_to_excel');

Inside Custom Javascript.js

    $('#llc-quote-details').on('click', '#exportExcelAndPDF', function() {
        var customersPo = $('#edited-customers-po').val();

        $.ajax({
            url: llcQuoteAutocomplete.ajaxurl,
            type: 'POST',
            data: {
                action: 'export_data_to_excel',
                customers_po: customersPo,
                nonce: llcQuoteAutocomplete.nonce,
            },
            success: function(response) {

            },
            error: function(xhr, status, error) {
                console.error(error); // Log any AJAX errors for debugging
            }
        });
    });

I am only testing first via Hello World because if this works, I can export any data now.

Well.

1. Setting up the headers to allow it

header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
    header('Content-Disposition: attachment; filename="hello_world.xlsx"');
    header('Cache-Control: max-age=0');

2. Tried Google Chrome, MS Edge, Mozilla Firefox but still cannot download.

Answer 1

This is a security feature of the Chrome engine and the Firefox Engine. You can use jQuery to click the link if the file is ready for the auto download.

$( document ).ready(function() {
    $('#SELECTOR FOR FILELINK').click();
});