VENTO

This is a minimal template engine inspired by other great engines like Nunjucks, Liquid, Mustache or EJS.

Why another template engine?

Because I couldn't find the "perfect" template engine for me (probably this one neither is). The issues I found in existing template engines:

Nunjucks

(It's my favorite template engine so far).

  • I like:
    • I can invoke functions like {{ user.getName() }}.
    • Very flexible, with many built-in filters and features
  • I don't like:
    • It's not well maintained. The last version was released in Jun 2022. And the previous version in 2020.
    • It's not async-friendly. For example, you have some tags to work with sync values (like for and if) and others for async values (like asyncEach and ifAysnc). Some features don't work in async contexts.
    • To me, it's very uncomfortable to have to type the delimiters {% and %} all the time (especially the % character).
    • By default, all variables are escaped, so you have to remember to use the safe filter everywhere. This is not very convenient for my use case (static site generators), where I can control all the content and the HTML generated.
    • Some filters are too specific.

Liquid

  • I like:

    • The support for async evaluation is less hacky than Nunjucks.
    • The variables are not escaped by default, there's an escape filter for that.

  • I don't like:

    • It's not possible to invoke functions in a liquid template. For example {{ user.getName() }} fails.
    • It has the same problem as Nunjucks with the % character in the delimiters.

EJS/Eta

  • I like:
    • It allows running any javascript code in the template.
  • I don't like:
    • It has the same problem with the % character. And I don't like the opening and closing delimiters (<% and %>).
    • Because it runs javascript, it's very verbose to do a simple forEach or if.

Mustache

  • I like:
    • Very simple, everything is inside {{ and }}.
    • The closing tag is {{/tagname}}, very nice!
  • I don't like:
    • Perhaps too simple and the syntax can be a bit confusing.
    • Partials. It's not easy to include them dynamically.
    • The data context is a bit confusing to me.
    • Very uncomfortable to work with filters.

What this new template engine has to offer?

First, let's take a look at this syntax example:

{{ if printName }}
  {{ await user.getName("full") |> toUpperCase }}
{{ /if }}
  • Everything is between {{ and }} tags. Unlike Nunjucks or Liquid, there's no distinction between tags {% tag %} and printing variables {{ var }}.
  • The closed tag is done by prepending the / character (like Mustache).
  • Async friendly.
  • Like EJS, you can use real JavaScript code everywhere. await user.getName("full") is real JS code that will be executed at runtime.
  • Filters are applied using the pipeline operator (|>). Note: this is not exactly like the last proposal for JavaScript, it's inspired by (the previous proposal that was rejected but it's way more simple and fits better for filters.
  • Filters can run prototype methods. In this example users.getName("full") returns a string, so the toUpperCase is a method of the String object. It's the same as users.getName("full").toUpperCase().

Getting started

This is a library for Deno. I'm planning to release an NPM version in the future.

First, you need to import the library and create an instance:

import vento from "https://deno.land/x/vento@v0.2.0/mod.ts";

const vto = vento({
  // Resolve the non-relative includes paths
  includes: "./path/to/includes",
});

There are different ways to load, compile and run a template. For example, you can use load to load and compile a template file and return it.

// Load and return a template
const template = vto.load("my-template.vto");

// Now you can use it passing the data
template({ title: "Hello world" });

Alternatively, you can load and run the template file in a single call:

vto.run("my-template.vto", { title: "Hello world" });

If the template code is not a file, you can run it directly:

vto.runString("<h1>{{ title }}</h1>", { title: "Hello world" });

Visual Studio Code Support

The Vento extension for VS Code enables syntax highlight and provides some useful snippets.

API

Read the docs