Adding multiple HTTP headers?

The CMS Questions
1

I’m trying to implement HTTP/2 Server Push with CSS files (and eventually javascript & images as well).

From what I understand, I can’t add HTTP headers into my templates or snippets; I have to add it to my configs. (Please correct me if I’m wrong because this would make things a lot easier if possible!)

In my config, I have code like this:

c::set('headers', array(
	'default' => function($page) {
		header('Link: </assets/normalize.css>; rel=preload');
		header('Link: </assets/global.css>; rel=preload');
		header('Link: </assets/modules.css>; rel=preload');
	}
));

According to Chrome, only the last header in the code is properly doing server push.

Any ideas?

2

Okay, I just figured it out. They have to be listed in the same line:

c::set('headers', array(
	'default' => function($page) {
		header('Link: </assets/normalize.css>; rel=preload, </assets/global.css>; rel=preload, </assets/modules.css>; rel=preload');
	}
));

But now I have another question: is it possible to preload/server push a dynamic list of assets? For example, preload all .css files that are attached to the current page?

3

The headers option looks for the current template. So you could create separate rules for each template. And then each callback gets the $page variable like in your example. You can use it to check for specific values and output headers based on the information.

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