CODEWITHSUNDEEP
javascriptcsstemplatesweborganization
Ryan Jendoubi
Ryan Jendoubi

Reputation: 303

When using (only) a templating system, how should I manage CSS, javascript etc for sub-templates?

I've had this same question when working with different templating systems in different languages in the past, so first,

The general question

I want to use a sub-template to include a certain UI component which might appear in different places on a number of different pages. This UI component requires certain CSS and JS files.

I want to Do The Right Thing with CSS and JS resources, which, as far as I know and in broad terms, is to a) combine as many as possible b) minify as much as possible and maybe c) put what I can at the end of my markup so the browser doesn't have to wait for them to load before displaying content.

So, if I've got various different UI components, as well as different headers and sidebars in different sections of the site, which all require their own special CSS and JS to function correctly, what's the best way for me to manage them through a templating system so that the final markup is as small and well-organised as possible?

Specifics of my situation

I'm working on a large legacy PHP site, on which, to give the original authors the benefit of the doubt, development may have begun before MVC became really mainstream, and before there were so many choices of frameworks around to use. So there is no consistent MVC framework, no routing, no templating (no ORM either, but that particular curse isn't as relevant here).

I'm going to have to keep things ticking over, squashing bugs and adding a few new features until a complete rewrite is usable, so I'm trying to breathe some sanity into things as I go along.

The easiest place to start seemed to be the views layer, for which I'm using TinyButStrong. An example of their sub-templates can be found here, but like I said, I think this is a very general question.

Things I've considered

With a more integrated framework I'd like to be able to do something like $view->add_js($foo), but transitioning to a full-blown framework is what other people are doing while I try keep the existing codebase seaworthy. There isn't even really enough consistent organisation of files to roll something like this by hand.

At the moment the best thing I can come up with is making a DOMDocument out of the view right before it's output and manipulating <link> and <script> tags at that point. I don't know if that's a bit crazy though. Given the generality of the problem I'd like to think that there's a known sensible way to go about it.

Many thanks for your input.

Upvotes: 2

Views: 184

Answers (2)

Ryan Jendoubi
Ryan Jendoubi

Reputation: 303

What you want in this situation is some form of template inheritance; that is, technology whereby a sub-template has access to areas in a 'parent' template, and can edit or replace content in those areas. Using this ability, CSS and JS required for a component included via a sub-template can be added in to the <head> element of the parent page.

In Twig, this is achieved using named blocks. First, you create your parent template (or layout, as it's called in Twig), e.g. index.html.twig. You include in it a named block like {% block myCss %}.

Next, to create a sub-template, you begin the template with the line {% extends ::index.html.twig %}. Then, the content of a block defined in the sub-template with the same name as a block in the parent template (in this case {% block myCSS %}) will get substituted into the parent template. To append rather than replace content in the parent template, use {{ parent() }} to include content already existing in the parent.

An example of this with code is available at the link given by @Basel Shishani. I've heard that Twig is modelled after Django, and template inheritance in Django looks very similar (with the exception of using {{ block.super }} instead of {{ parent() }}. There is a discussion of how to achieve the same ends in TinyButStrong.

As a wider point, the Assetic library looks like a very promising solution for managing CSS and JS assets, in order to avoid duplication (e.g. where the same JS file is required by multiple components/subtemplates), enable concatenation and minification of assets, and more. This presentation of its features gives more details.

Upvotes: 0

Basel Shishani
Basel Shishani

Reputation: 8187

It's hard for the reader to know what can or cannot be done with your code base. A common way to handle this situation would be to pass parameters to the view template, and the template can then include conditional chunks or include sub-templates based on your parameters. This does not require a full-fledged framework, a stand-alone template engine should do. If your template engine supports inheritance there is a nice pattern for handling assets in your templates - check here for example http://symfony.com/doc/2.0/book/templating.html.

Manipulating the Dom for each request to handle this kind of thing seems bit unorthodox.

Upvotes: 1

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