Questa è compilata per PHP:

<?php
require('fpdf.php');

class PDF_Javascript extends FPDF {

var $javascript;
var $n_js;

function IncludeJS($script) {
$this->javascript=$script;
}

function _putjavascript() {
$this->_newobj();
$this->n_js=$this->n;
$this->_out('<<');
$this->_out('/Names [(EmbeddedJS) '.($this->n+1).' 0 R ]');
$this->_out('>>');
$this->_out('endobj');
$this->_newobj();
$this->_out('<<');
$this->_out('/S /JavaScript');
$this->_out('/JS '.$this->_textstring($this->javascript));
$this->_out('>>');
$this->_out('endobj');
}

function _putresources() {
parent::_putresources();
if (!empty($this->javascript)) {
$this->_putjavascript();
}
}

function _putcatalog() {
parent::_putcatalog();
if (isset($this->javascript)) {
$this->_out('/Names <</JavaScript '.($this->n_js).' 0 R>>');
}
}
}
?>

Example
This example shows how to start printing as soon as the document opens. It is possible to launch the print dialog (pass true to the AutoPrint() method), or directly print with default parameters (pass false).

<?php
define('FPDF_FONTPATH','font/');
require('fpdf_js.php');

class PDF_AutoPrint extends PDF_Javascript
{
function AutoPrint($dialog=false)
{
//Embed some JavaScript to show the print dialog or start printing immediately
$param=($dialog ? 'true' : 'false');
$script="print($param);";
$this->IncludeJS($script);
}
}

$pdf=new PDF_AutoPrint();
$pdf->Open();
$pdf->AddPage();
$pdf->SetFont('Arial','',20);
$pdf->Text(90, 50, 'Print me!');
//Launch the print dialog
$pdf->AutoPrint(true);
$pdf->Output();
?>

Grazie per l'attenzione.