Why use DOMDocument instead of PHP with HTML?

Question

I still can't really wrap my head around the built in DOMDocument class.

Why should I use that instead of just doing it similar to the following?

I would like to know the benefits.

$URI    = $_SERVER['REQUEST_URI'];
$navArr = Config::get('navigation');

$navigation = '<ul id="nav">' . "\n";
foreach($navArr as $name => $path) {
    $navigation .= '    <li' . ((in_array($URI, $path)) ? ' class="active"' : false) . '><a href="' . $path[1] . '">' . $name . '</a></li>' . "\n";
}
$navigation .= '</ul>' . "\n\n";

return $navigation;

If you're constructing HTML for output then DOMDocument is overkill. If you're scraping HTML from a site to extract data from it DOMDocument is the only reliable way to parse the HTML. (Don't try regex for that. See [this answer](http://stackoverflow.com/a/1732454/1864610)) — , Apr 26 '14 at 01:50

Alf Eaton · Accepted Answer · 2014-04-29T16:30:24.600

Here's the same example using DOMDocument:

$doc = new DOMDocument;

$list = $doc->appendChild($doc->createElement('ul'));
$list->setAttribute('id', 'nav');

foreach ($navArr as $name => $path) {
  $listItem = $list->appendChild($doc->createElement('li'));

  if (in_array($URI, $path)) {
    $listItem->setAttribute('class', 'active');
  }

  $link = $listItem->appendChild($doc->createElement('a'));
  $link->setAttribute('href', $path[1]);
  $link->appendChild($doc->createTextNode($name));
}

return $doc->saveHTML();

It's more verbose, but not too much, and possibly clearer what's happening at each step.

One benefit is character escaping: createTextNode and setAttribute ensure that the special HTML characters (quotes, ampersands and angle brackets) are escaped properly.

In the end, though, for a larger application, you'd probably want to use an actual templating language like Twig for generating HTML, as the templates are more readable and extensible.

Why use DOMDocument instead of PHP with HTML?

1 Answers1