crafting (and) JavaScript

Choosing a new Template Engine

I have been using tundra as template engine for this site. And I am thankful for it, but it's time to move on. I mainly chose it because it is tiny, has no dependencies and it has the features I was looking for. It just does the things I am used to from django-like template engines not well enough, misses a tiny useful feature here and there. This does especially hurt, when I want to reuse HTML sceletons, tags, HTML snippets or functions to generate them. That is where tundra stops working. Knowing the code a bit I also think I have a feeling that getting it there would be quite some work.

Instead of helping out with tundra and getting it there, I decided to invest my time in just being a user and issue reporter. This can become a time eater, so I prefer to invest my time in the things I am more passionate about and use one of the many template engines that exist. Read on to find out how I am choosing and which one I will decide to use.

What am I Looking for?

I am heavily influenced by my former experience with template engines. It started out in PHP times, where PHP itself was a very powerful template engine, over to using various different ones there. Some of them had also been very restrictive in their feature set, in the hope to make better code, this never convinced me.

When I used django and the template engine that came with, this felt very good and I felt being productive. It left some freedom to the author, one could extend it with own template tags and the logic inside the templates was possible to be complex, but if one behaves well it can be very simple and concise. This is the kind of template engine I would like to have. Oh, and I had some exposure to ejs, handlebars, etc. too - let's stay with the django style engine ;).

The feature that (I know now) I am looking for:

  • extending and nested templates, for making reuse of templates, e.g. via {% extends "base.html" %} (in django)
  • extending/overriding (nested) blocks, with default content (not possible with tundra) (in django)
  • loops, conditionals, variables, escaping, raw string printing, whitespace handling

I do not want:

  • a lot of dependencies
  • a complex system/language

I do not necessarily need:

  • filtering, sorting, etc. in the template, I am fine doing that in code, sounds much more reasonable to me
  • i18n, l10n - I have no plan to make my blog (or any site, I use site-stitcher with) multilingual

Searching on Codeberg First

None of the results on codeberg.org when searching for "template engine" seems to be anything useful. Too bad. It would have received a lot of additional bonus points from me, I would maybe even have considered helping out. Moving on.

Art Template

Website: https://aui.github.io/art-template
Repo: https://github.com/aui/art-template

The page advertises with "High performance JavaScript templating engine". I am quite tired of those. In the end I decide how fast is fast enough and what one compares it to. The main feature mentioned in the README is "performance is close to the JavaScript rendering limits". Sounds like a sales show. But ok, I know to not see this ;) ... well, I got a little biased, negatively.

The first con I see is the mentioning of webpack in multiple places. This makes me feel as if there are dependencies that I don't want to buy in to. The devDeps list webpack, prettier, eslint, prettier. Too many tools for my taste. But that is state of the art nowadays and that might not be a bad thing, it could also mean that quality is important, could also be just the default set of tools. Who knows.

In the package.json I also see acorn, escodegen, estraverse. Nice, this means to me there is no magic regex and string handling going on, but a certain level of professional AST processing. Sounds nice. Some points on the pro side from me.

In the features list I see the first three items that are of no interest to me, super fast, debug friendly and super compatible. But the fourth one "support template inheritance and sub template" is on my must-have list. Cool, another pro. Feature number five "browser version is only 6KB" I do not care about. I am just doing server-side, so I may better look that this works too.

In the package.json I also saw babel, which I am not really fond of, I think that era is behind us we have our JS engines be up to date very quickly, so I prefer less tooling and maybe not use a new feature. But with the latest engines we have a lot of great features in the language and available everywhere, so no need (for me) to transpile.

One more con, while reading some source code, it is documented in japanese (I think this is). Fortunately the functions are named in english. There are a good number of tests though, that's definitely a pro.

This one stays in the game.

Template 7

Website: https://idangero.us/template7/#.X-s39y337Vs
Repo: https://github.com/nolimits4web/template7

"Mobile-first JavaScript Template Engine" - say what? Can I run it on the server too? What can be mobile about a template engine. I assume having it run on the client. Whatelse, could I imagine to be mobile-first?

Absolutely no dependency, as the package.json lists? Only devDeps? Wow.

I can download the repo or install it via bower. Aehm, no. I am moving on.


Repo: https://github.com/paularmstrong/swig

As far as I remember this is the JavaScript version of the django template engine. But it is unmaintained, the repo is even archived. Oh no. I assume there are suggested alternatives. Gotta read around a bit.


Repo: https://github.com/PaulGuo/Juicer

The website does not work, docs are in japanese. I am out.

New Search Tactics

Maybe my search for "javascript template engine" github was not so clever. I might reconsider this now. Searching for javascript template engine swig I stumbled over js.libhunt not very promising, but in the end I ended up with a list of engines to look at:

  • https://squirrelly.js.org
  • https://github.com/jasonmoo/t.js - no matter how old, I love the minimalistic set of features, unfortunately not enough for my purposes now
  • http://www.dustjs.com - looks like it has all the features, but I am dismissing it for its very minimalistic and therefore not expressive enough template syntax, I strongly prefer more characters so any random code-reader can understand what't going on, as opposed to using the minimal set of characters (for now useful reason)
  • https://github.com/twitter/hogan.js - from what I understand this is made for snippets, I can imagine it is used for the twitter embed functionality, I am dismissing it (maybe too early, but fine for me)

Found it, Decided, Done

Website: https://mozilla.github.io/nunjucks/
Repo: https://github.com/mozilla/nunjucks

I found the one I am using. Sorry, I am jumping all my structured evaluations that I started above. I have intuitively and emotionally decided for nunjucks because:

  • it is done by mozilla, a company who's vision I love
  • the syntax is just what I am looking for (jinja, swig, django inspired)
  • I saw it and knew I want this syntax
  • reading the docs I see there is extends, block, macro, etc. - all I need, I believe

I am ignoring:

  • further evaluation if all the features are supported that I need
  • the many dependencies it carries along (mostly dev deps)
  • anything else.

I am sold. Done. Over and out.