How to open pdf on button?

Question

PHP

there is a pdf.php file that opens a pdf generated from html code.
I want that when the button is clicked, data is sent to this file and pdf is opened depending on the data received.
Tried to write jquery:

$('#button').on('click', function () {
        var params = {...};
        $.post('pdf.php', params);
    });

And the data goes away (status 200), but the pdf does not open, although if you open pdf.php in the browser, the pdf file opens.
Here is the content of pdf.php:

<?php

ob_start();
include 'pdfInvoice.php';
$html = ob_get_contents();
ob_end_clean();

include("mpdf60/mpdf.php");

$mpdf = new mPDF('utf-8', 'A4', '12', '', 10, 10, 7, 7, 10, 10);

$stylesheet = file_get_contents('css/invoice.css'); //подключаем css
$mpdf->WriteHTML($stylesheet, 1);

$mpdf->WriteHTML($html, 2); //формируем pdf
$mpdf->Output('invoice.pdf', 'I');

And in the pdfInvoice.php file there is a table in html

Answer 1

Ajax will not download.
button/ajax replace with regular <a href="pdf.php?...">Скачать pdf</a>
Update: ... or with

<form action="pdf.php?..."><input type="submit" value="Скачать pdf"></form>