"Preview" mpdf directly to browser - php

Question

I'm using mpdf and writing a bunch of HTML to the pdf object via mpdf::writeHTML(). Is there any way, rather than outputting an PDF, to simply dump it right back to the browser instead? So, rather than creating the PDF just write it out as a web page?
I want to give the user the option of a PDF or a web page, and rather than branching off for echo or writeHTML for each line, I'd like to build the document and then either output web or PDF.
EDIT TO ADD:
Something like this:
$mpdf = new mpdf();
$mpdf->writeHTML( "<p>Hello World</p>" );
$mpdf->addPage( 'L' );
$mpdf->writeHTML( "<p>Lorem ipsum egg foo yung.</p>" );
if( $_GET['format'] == 'pdf' ) {
$mpdf->output(); //spit out a PDF
} elseif ( $_GET['format'] == 'web' ) {
echo $mpdf->contents_as_html(); // write a web page
}
I'm currently writing each line to a giant string, and then either passing the string to mpdf::writeHTML() or echo; but this doesn't allow me to use various mpdf functions such as addPage(), bookmark(), and so forth.

Answer 1

This is what I did, per a suggestion by #CBroe. When writeHTML() is called, it writes to an internal variable $this->strHTML, and then does its normal process. If the object is cast to string, it returns $this->strHTML
class myPDF extends Mpdf {
private $strHtml = '';
public function writeHTML( $html, $mode = 0, $init = true, $close = true ) {
$this->strHtml .= $html . "\n";
return parent::writeHTML( $html, $mode, $init, $close );
}
public function __toString() {
return $this->strHtml;
}
}

Answer 2

You can choose the output with mPDF by changing the second parameter.
I = send the file inline to the browser.
F enter code here= save to a local file with the name given by $filename.
S = return the document as a string. $filename is ignored.
D = send to the browser and force a file download with the name given by $filename.
Output mPDF:
$mpdf->Output($filename, "I"); // Change "I" to your preferred output
If you choose output the file in your browser, just make sure that you target the output on an empty page. Otherwise it's possible that the header and footer will interfere.
Artikel mPDF output:
https://mpdf.github.io/reference/mpdf-functions/output.html