Using DOMDocument to Modify HTML with PHP
One of the first things you learn when wanting to implement a service worker on a website is that the site requires SSL (an https address). Ever since I saw the blinding speed service workers can provide a website, I've been obsessed with readying my site for SSL. Enforcing SSL with .htaccess was easy -- the hard part is updating asset links in blog content. You start out by feeling as though regular expressions will be the quick cure but anyone that has experience with regular expression knows that working with URLs is a nightmare and regex is probably the wrong decision.
The right decision is DOMDocument, a native PHP object which allows you to work with HTML in a logical, pleasant fashion. You start by loading the HTML into a DOMDocument instance and then using its predictable functions to make things happen.
// Formats post content for SSL
function format_post_content($content = '') {
$document = new DOMDocument();
// Ensure UTF-8 is respected by using 'mb_convert_encoding'
$document->loadHTML(mb_convert_encoding($content, 'HTML-ENTITIES', 'UTF-8'));
$tags = $document->getElementsByTagName('img');
foreach ($tags as $tag) {
$tag->setAttribute('src',
str_replace('http://davidwalsh.name',
'https://davidwalsh.name',
$tag->getAttribute('src')
)
);
}
return $document->saveHTML();
}
In my example above, I find all img elements and replace their protocol with https://. I will end up doing the same with iframe src, a href, and a few other rarely used tags. When my modifications are done, I call saveHTML to get the new string.
Don't fall into the trap of trying to use regular expressions with HTML -- you're in for a future of failure. DOMDocument is lightweight and will make your code infinitely more maintainable.
![CSS Filters]()
CSS filter support recently landed within WebKit nightlies. CSS filters provide a method for modifying the rendering of a basic DOM element, image, or video. CSS filters allow for blurring, warping, and modifying the color intensity of elements. Let's have...
![9 More Mind-Blowing WebGL Demos]()
With Firefox OS, asm.js, and the push for browser performance improvements, canvas and WebGL technologies are opening a world of possibilities. I featured 9 Mind-Blowing Canvas Demos and then took it up a level with 9 Mind-Blowing WebGL Demos, but I want to outdo...
![MooTools OpenLinks Class – Updated]()
A long time back I coded a MooTools class called OpenLinks. The class is quite useful but the code...sucks. I've gotten much better with MooTools over the past years so I thought I'd go back and update the class to be better, faster...
![External Site Link Favorite Icons Using MooTools and CSS]()
I recently came upon an interesting jQuery article about how you can retrieve all external links within a page, build the address of the site's favorite icon, and place the favorite icon along side the link. I've chosen a different approach which...
So do you know if there is a performance hit with creating an element using this vs creating a string of html?
The right decision is skipping domain entirely if it isn’t hosted on some subdomain (
/path/to/asset), and skipping protocol if it is ((//example.com/path/to/asset)David, rather than str_replace all your (internal)
http://strings withhttps://you should replace them with//– that way your links become protocol-agnostic — a more future-proof solution.Why don’t you use the
search-replacefunction in WP-CLI?Why not remove the protocol completely?
//davidwalsh.name/would default to whatever protocol is used in the address bar.I agree that
//would be better but some RSS feed readers usehttp, othershttps. I’m asserting complete control.