Skim

Take the fat out of your client-side templates with Skim. Skim is the Slim templating engine with embedded CoffeeScript. It compiles to JavaScript templates (.jst), which can then be served by Rails or any other Sprockets-based asset pipeline.

Usage

gem install skim, or add skim to your Gemfile in the :assets group:

group :assets do
  gem 'skim'
end

Create template files with the extension .jst.skim. For example, test.jst.skim:

p Hello #{@world}!

In your JavaScript or CoffeeScript, render the result, passing a context object:

$("body").html(JST["test"]({world: "World"}));

Order up a skinny latte and enjoy!

Caveats

Skim is an early proof-of-concept. Some Slim features are still missing:

• Skim does not currently support embedded engines. Being a client-side templating languages, it will only be able to support embedded engines with a client-side implementation.
• Skim does not currently support HTML pretty-printing (Slim's :pretty option). This is low priority, as pretty-printing is even less important client-side than server-side.
• Skim does not currently support backslash line continuations.

Language reference

Skim supports the following Slim language features:

• doctype declarations (doctype)
• HTML Comments (/!) and conditional comments (/[...])
• static content (same line and nested)
• dynamic content, escaped and not (= and ==)
• control logic (-)
• string interpolation, escaped and not (#{} and #{{}})
• id and class attribute shortcuts (# and .)
• attribute and attribute value wrappers
• logic-less (sections) mode

Several Coffee/JavaScript considerations are specific to Skim:

• When interpolating the results of evaluating code, Skim will replace null and undefined results with an empty string.
• You will typically want to use the fat arrow => function definition to create callbacks, to preserve the binding of this analogously to how self behaves in a Ruby block.

The context object

The context object you pass to the compiled template function becomes the value of this inside your template. You can use CoffeeScript's @ sigil to easily access properties and call helper methods on the context object.

Escaping and unescaping

Like Slim, Skim escapes dynamic output by default, and it supports the same == and #{{}} syntaxes for bypassing escaping. In addition, the special safe method on the context object tells Skim that the string can be output without being escaped. You can use this in conjunction with escape context method to selectively sanitize parts of the string. For example, given the template:

= @linkTo(@project)

you could render it with the following context:

JST["my_template"]
  project: { id: 4, name: "Crate & Barrel" }
  linkTo: (project) ->
    url  = "/projects/#{project.id}"
    name = @escape project.name
    @safe "<a href='#{url}'>#{name}</a>"

to produce:

<a href='/projects/4'>Crate &amp; Barrel</a>

The Skim asset

By default, all you need to do to start using Skim is add it to your Gemfile. Skim will embed a small amount of supporting code in each generated template asset. You can remove this duplication by manually including Skim's asset, and setting Skim's :use_asset option to true.

In Rails, this can be done by adding the following to application.js:

//= require skim

And the following in an initializer:

Skim::Engine.default_options[:use_asset] = true

License (MIT)

Copyright (c) 2012 John Firebaugh

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Special Thanks

• Andrew Stone, for Slim
• Magnus Holm, for Temple
• Daniel Mendler, for maintenance of both