Haml Coffee Templates

Haml Coffee is a JavaScript templating solution that uses Haml as markup, understands inline CoffeeScript and generates a JavaScript function that renders to HTML. It can be used in client-side JavaScript applications that are using Backbone.js, Spine.js, JavaScriptMVC, KnockoutJS and others, or on the server-side in frameworks like Express.

Contents

• Installation
  • Integration
• Compile Haml Coffee
  • Using the API
  • Using with Express
  • Using the CLI tool
• Haml support
• CoffeeScript support
  • Attributes
  • Running code
  • Filter
• Compiler options
  • HTML generation options
  • Custom helper function options
• Development information

Haml Coffee is available in NPM and can be installed with:

$ npm install haml-coffee

Please have a look at the CHANGELOG when upgrading to a newer Codo version with npm update.

If you're using Hem to manage your CommonJS modules, use hem-haml-coffee. This is excellent for developing your Spine application.

If you like to integrate Haml Coffee seamless into the Rails asset pipeline, check out haml_coffee_assets.

For using the Haml Coffee compiler in the browser, a browserified version is provided in the dist/compiler directory: Haml Coffee compiler (minified)

You can compile a Haml Coffee template to a JavaScript function and execute the function with the locals to render the HTML. The following code

hamlc = require 'haml-coffee'
tmpl = hamlc.compile '%h1= @title'
html = tmpl title: 'Haml Coffee rocks!'

will create the HTML <h1>Haml Coffee rocks!</h1>.

The compile function can take the compiler options as second parameter to customize the template function:

hamlc.compile '%h1= @title'
  cleanValue: false
  escapeHtml: false

See the compiler options for detailed information about all the available options and browse the codo generated Haml-Coffee API documentation.

You can configure Express to use Haml Coffee as template engine:

express = require 'express'
hamlc = require 'haml-coffee'

app = express.createServer()
app.register '.hamlc', hamlc

Express uses a layout file layout.hamlc by default and you have to insert the rendered view body into the layout like this:

!!!
%head
  %title Express App
%body
  != @body

Now you can create a Haml Coffee view

%h1= "Welcome #{ @name }"
%p You've rendered your first Haml Coffee view.

that you can render with:

app.get '/', (req, res) ->
  res.render 'index.hamlc', name: 'Express user'

You can also turn off the layout rendering by configure the view options:

app.set 'view options', layout: false

See the compiler options for detailed information about all the available options.

It's possible to use Haml Coffee as the default template engine by setting the view engine:

app.configure ->
  app.set 'view engine', 'hamlc'

which allows you to omit the .hamlc extension when rendering a template:

app.get '/', (req, res) ->
  res.render 'index', name: 'Express user'

You can read more about the view rendering in the Express documentation.

After the installation you will have a haml-coffee binary that can be used to compile single templates and even compile multiple templates recursively into a single file.

$ haml-coffee
Usage: node haml-coffee

Options:
  -i, --input                        Either a file or a directory name to be compiled
  -o, --output                       Set the output filename
  -n, --namespace                    Set a custom template namespace
  -t, --template                     Set a custom template name
  -b, --basename                     Ignore file path when generate the template name

The following section describes only the options that are unique to the command line tool.

You can see all the available options by executing haml-coffee --help and have a look at the compiler options for detailed information about all the options.

Input filename

You can either specify a single template or a directory with the -i/--input argument. When you supply a directory, templates are being searched recursively:

$ haml-coffee -i template.haml

This will generate a template with the same name as the file but the extension changed to .jst. The above command for example would generate a template named template.jst.

A valid Haml Coffee template must have one of the following extensions: .haml, .html.haml, .hamlc or .html.hamlc.

Output filename

You can specify a single output file name to be used instead of the automatic generated output file name with the -o/--output argument:

$ haml-coffee -i template.haml -o t.js

This creates a template named t.js. You can also set a directory as input and give an output file name for concatenating all templates into a single file:

$ haml-coffee -i templates -o all.js

This will create all the templates under the templates directory into a single, combined output file all.js.

Template namespace

Each template will register itself by default under the window.HAML namespace, but you can change the namespace with the -n/--namespace argument:

$ haml-coffee -i template.haml -n exports.JST

Template name

Each template must have a unique name under which it can be addressed. By default the template name is derived from the template file name by stripping off all extensions and remove illegal characters. Directory names are converted to nested namespaces under the default namespace. For example, a template named user/show-admin.html.haml will result in a template that can be accessed by window.HAML['user/show_admin'].

Given the -b/--basename argument, the deduced template name will not include the path to the template. For example, a template named user/show-admin.html.haml will result in a template that can be accessed by window.HAML['show_admin'] instead of window.HAML['user/show_admin'].

With the -t/--template argument you can set a template name manually:

$ haml-coffee -i template.haml -n exports.JST -t other

This will result in a template that can be accessed by exports.JST['other'].

Haml Coffee implements the Haml Spec to ensure some degree of compatibility to other Haml implementations and the following sections are fully compatible to Ruby Haml:

• Plain text
• Multiline: |
• Element names %
• Attributes: {} or ()
• Class and ID: . and #, implicit div elements
• Self-closing tags: /
• Doctype: !!!
• HTML comments: /, conditional comments: /[], Haml comments: -#
• Running CoffeeScript: -, inserting CoffeeScript: =
• CoffeeScript interpolation: #{}
• Whitespace preservation: ~
• Whitespace removal: > and <
• Escaping \
• Escaping HTML: &=, unescaping HTML: !=
• Filters: :plain, :javascript, :css, :cdata, :escaped, :preserve
• Boolean attributes conversion

Please consult the official Haml reference for more details.

Haml Coffee supports both Ruby 1.8 and Ruby 1.9 style attributes. So the following Ruby 1.8 style attribute

%a{ :href => 'http://haml-lang.com/' } Haml

can also be written in Ruby 1.9 style:

%a{ href: 'http://haml-lang.com/' } Haml

Helpers

Haml Coffee supports a small subset of the Ruby Haml helpers:

Surround

Surrounds a block of Haml code with strings, with no whitespace in between.

= surround '(', ')', ->
  %a{:href => "food"} chicken

produces the HTML output

(<a href='food'>chicken</a>)

Succeed

Appends a string to the end of a Haml block, with no whitespace between.

click
= succeed '.', ->
  %a{:href=>"thing"} here

produces the HTML output

click
<a href='thing'>here</a>.

Precede

Prepends a string to the beginning of a Haml block, with no whitespace between.

= precede '*', ->
  %span.small Not really

produces the HTML output

*<span class='small'>Not really</span>

Haml and CoffeeScript are a winning team, both use indention for blocks and are a perfect match for this reason. You can use CoffeeScript instead of Ruby in your Haml tags and the attributes.

It's not recommended to put too much logic into the template.

When you define an attribute value without putting it into quotes (single or double quotes), it's considered to be CoffeeScript code to be run at render time. By default, attributes values from CoffeeScript code are escaped before inserting into the document. You can change this behaviour by setting the appropriate compiler option.

HTML style attributes are the most limited and can only assign a simple variable:

%img(src='/images/demo.png' width=@width height=@height alt=alt)

Both the @width and @height values must be passed as locals when rendering the template and alt must be defined before the %img tag.

Ruby style tags can be more complex and can call functions:

%header
  %user{ :class => App.currentUser.get('status') }= App.currentUser.getDisplayName()

Attribute definitions are also supported in the Ruby 1.9 style:

%header
  %user{ class: App.currentUser.get('status') }= App.currentUser.getDisplayName()

More fancy stuff can be done when use interpolation within a double quoted attribute value:

%header
  %user{ class: "#{ if @user.get('roles').indexOf('admin') is -1 then 'normal' else 'admin' }" }= @user.getDisplayName()

But think about it twice before putting such fancy stuff into your template, there are better places like models, controllers or helpers to put heavy logic into.

You can define your attributes over multiple lines and the next line must not be correctly indented, so you can align them properly:

%input#password.hint{ type: 'password', name: 'registration[password]',
                      data: { hint: 'Something very important', align: 'left' } }

In the above example you also see the usage for generating HTML5 data attributes.

You can run any CoffeeScript code in your template:

- for project in @projects
  - if project.visible
    .project
      %h1= project.name
      %p&= project.description

There are several supported types to run your code:

• Run code without insert anything into the document: -
• Run code and insert the result into the document: =

All inserted content from running code is escaped by default. You can change this behaviour by setting the appropriate compiler option.

There are three variations to run code and insert its result into the document, two of them to change the escaping style chosen in the compile option:

• Run code and do not escape the result: !=
• Run code and escape the result: &=
• Preserve whitespace when insert the result: ~

Again, please consult the official Haml reference for more details. Haml Coffee implements the same functionality like Ruby Haml, only for CoffeeScript.

Functions

You can also create functions that generate Haml:

- sum = (a, b) ->
  %div
    %span= a
    %span= b
    %span= a+b
= sum(1,2)
= sum(3,4)

or pass generated HTML output through a function for post-processing.

= postProcess ->
  %a{ href: '/' }

In addition to the :plain, :javascript, :css, :cdata, :escaped and :preserve filters, which are also provided by Ruby Haml, Haml Coffee has a :coffeescript filter.

The content of the :coffeescript filter is run when the template is rendered and doesn't output anything into the resulting document. This comes in handy when you have code to run over multiple lines and don't want to prefix each line with -:

%body
  :coffeescript
    tags = ['CoffeeScript', 'Haml']
    project = 'Haml Coffee'
  %h2= project
  %ul
    - for tag in tags
      %li= tag

The following section describes all the available compiler options that you can use through the JavaScript API, as Express view option or as argument to the command line utility.

The command line arguments may be slightly different. For example instead of passing --escape-html=false you have to use the --disable-html-escaping argument. You can see a list of all the command line arguments by executing haml-coffee --help.

The HTML options change the way how the generated HTML will look like.

Output format

• Name: 'format'
• Type: String
• Default: html5

The Haml parser knows different HTML formats to which a given template can be rendered and it must be one of:

• xhtml
• html4
• html5

Doctype, self-closing tags and attributes handling depends on this setting. Please consult the official Haml reference for more details.

Uglify output

• Name: uglify
• Type: Boolean
• Default: false

All generated HTML tags are properly indented by default, so the output looks nice. This can be helpful when debugging. You can skip the indention by setting the uglify option to false. This save you some bytes and you'll have increased rendering speed.

HTML escape

• Name: htmlEscape
• Type: Boolean
• Default: true

The reserved HTML characters ", ', &, < and > are converted to their HTML entities by default when they are inserted into the HTML document from evaluated CoffeeScript.

You can always change the escaping mode within the template to either force escaping with &= or force unescaping with !=.

Attributes escape

• Name: escapeAttributes
• Type: Boolean
• Default: true

All HTML attributes that are generated by evaluating CoffeeScript are also escaped by default. You can turn of HTML escaping of the attributes only by setting escapeAttributes to false. You can't change this behaviour in the template since there is no Haml markup for this to instruct the compiler to change the escaping mode.

Clean CoffeeScript values

• Name: cleanValue
• Type: Boolean
• Default: true

Every output that is generated from evaluating CoffeeScript code is cleaned before inserting into the document. The default implementation converts null or undefined values into an empty string.

Preserve whitespace tags

• Name: preserve
• Type: String
• Default: textarea,pre

The preserve option defines a list of comma separated HTML tags that are whitespace sensitive. Content from these tags must be preserved, so that the indention has no influence on the displayed content. This is simply done by converting the newline characters to their equivalent HTML entity.

Autoclose tags

• Name: autoclose
• Type: String
• Default: meta,img,link,br,hr,input,area,param,col,base

The autoclose option defines a list of tag names that should be automatically closed if they have no content.

Haml Coffee provides helper functions for HTML escaping, value cleaning and whitespace preservation, which must be available at render time. By default every generated template function is self-contained and includes all of the helper functions.

However you can change the reference to each helper function by providing the appropriate compiler option and there are good reasons to do so:

• You want to reduce the template size and provide all the helpers from a central place.
• You want to customize a helper function to better fit your needs.

To change these functions, simply assign the new function name to one of the following options:

• customHtmlEscape: Escape the reserved HTML characters into their equivalent HTML entity.
• customPreserve: Converting newlines into their HTML entity.
• customFindAndPreserve: Find whitespace sensitive tags and preserve their content.
• customCleanValue: Clean the value that is returned after evaluating some inline CoffeeScript.
• customSurround: Surrounds a block of Haml code with strings, with no whitespace in between.
• customSucceed: Appends a string to the end of a Haml block, with no whitespace between.
• customPrecede: Prepends a string to the beginning of a Haml block, with no whitespace between.

You can find a default implementation for all these helper functions in the dist/helpers directory: CoffeeScript JavaScript

You'll need the latest version of node.js, npm, coffee-script and jasmine-node to run everything. Start the CoffeeScript compilation in the project root directory by running:

$ cake watch

And run the tests by calling:

$ jasmine-node

You can optionally install Guard with the Ruby Bundler:

$ bundle install

and run Guard to automatically compile your CoffeeScripts and run the Jasmine specs on file modification:

$ bundle exec guard

Changelog

Feel free to take a look at the crispy changelog instead of crawling through the commit history.

Related projects

Haml Coffee in the Rails asset pipeline:

• haml-coffee-assets

Authors

• Michael Kessler (@netzpirat)
• Sebastion Deutsch (@sippndipp)
• Jan Varwig (@agento)

Development is sponsored by 9elements and mksoft.ch.

Contributors

See all contributors on the contributor page.

License

(The MIT License)

Copyright (c) 2011-2012 9elements, Michael Kessler

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.