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a NodeJS and browser templating language based on coffeescript, with the slickest syntax ever

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README.md

TOFFEE

Toffee is a templating language developed at OkCupid, based on the simplicity and beauty of CoffeeScript.

  • it works with nodeJS (including Express 2.x and 3.x)
  • it works in the browser, too!
  • it does not require that you use CoffeeScript elsewhere in your project.

Table of Contents

Language Basics

Printing variables in Toffee is easy. Just use CoffeeScript's #{} syntax:

<div class="welcome">
   Hey, #{user.name}. 
   #{flirty_welcome_msg}
</div>

The #{} syntax is powerful, so be responsible.

<p>
  You have #{(limb for limb in limbs when limb.hasHand()).length} arms worth keeping.
</p>

Including other files is possible thanks to the function partial. This works in both Express and the browser.

<p>
   #{partial "navigation.toffee", {username: user.name, age: 22} }
</p>

But the greatest pleasure arises when you enter coffee mode. Note the {# ... #} region, where you can write multiple lines of CoffeeScript.

<p>
  {#
    ten_numbers = (Math.random() for i in [0...10])
    ten_numbers.sort (a,b) -> b - a
  #}
  The largest number I can even think of is #{ten_numbers[0]}.
</p>

Against all odds, inside coffee mode, you can switch back to toffee mode with {: ... :}. It's endlessly nestable.

<div class="wrapper">
 <div class="projects">
  {#
     if projects.length
      for project in projects {:
        <div class="project">
          <a href="#{project.url}">#{project.name}</a>
        </div>
      :}
  #}
 </div>
</div>

This bracket and nesting syntax avoids a lot of large, ugly regions, such as EJS's unethical <% } %>. It's been wrong for thousands of years to have control markers surrounded by other control markers, and it is still wrong. Witness:

EJS, verbose and weak.

<% for(var i=0; i<supplies.length; i++) {%>
   <li><%= supplies[i] %></li>
<% } %>

TOFFEE, so elegant and proud.

{# 
  for supply in supplies {:<li>#{supply}</li>:} 
#}

Or, using Toffee's print:

{# 
  for supply in supplies 
    print "<li>#{supply}</li>"
#}

These are slightly different, as print outputs raw text, while #{} used in toffee mode safely escapes for HTML. This escaping is customizable. More on that below.

With nested code, indentation of your CoffeeScript is magically maintained.

{#
   for name, profile of friends when profile.is_responsible {:
      <p>
        You know, #{name} would make a great designated driver.
        And she only lives #{profile.distance}km away.
        {#
           if profile.cars.length {: And wow, she drives a #{profile.cars[0].model} :}
           else                   {: But, alas, she has no wheels. :}
        #}
      </p>
   :}
#}

By now, you probably have questions about indenting

Since CoffeeScript is sensitive to indenting, so is Toffee.

But...Toffee doesn't care where you start your CoffeeScript. When you want to create a coffee block, you can indent it however you like, and all that matters is that the internal, relative indenting is correct. For example, these are identical:

<p>
    {#
          if user.is_awesome {:
            YAY!
          :}          
    #}
</p>
<p>
{#
if user.is_awesome {:
  YAY!
:}
#}
</p>

In other words, feel free to pick whatever indentation baseline you want when entering a region of CoffeeScript.

Note that where you put your toffee mode tokens ({:) is important, as the following illustrates:

<p>
 {#
    if x is true
      if y is true
        if z is true
          w = true
      {: 
        x is true! Dunno anything about y or z, though. 
      :}
 #}
</p>

Why? Because this is roughly the same as saying:

<p>
 {#
    if x is true
      if y is true
        if z is true
          w = true
      print "\n       x is true! Dunno anything about y or z, though.\n     "
 #}
</p>

One syntactic convenience: if you start a {: on the same line as some preceeding CoffeeScript, it's treated the same as putting it on a new line and indenting one level. So the following three conditionals are the same:

{#
  if x is true
    {:yay:}
#}
{#
  if x is true {:yay:}
#}
{#
  if x is true {:
    yay
  :}
#}

The third example has extra whitespace around the "yay," but otherwise the three are logically identical.

One gotcha with indenting

THIS IS AN ERROR

{# if x is 0 {:Yay!:}
   else      {:Burned:}
#}

Note that the indentations before the 'if' and the 'else' are technically different, as the if has only 1 space before it, and the else has 2. This is better style anyway:

GOOD

{# 
   if x is 0 {:Yay!:}
   else      {:Burned:}
#}

With a single line of CoffeeScript, feel free to keep it all on one line:

GOOD

<div>{# foo = "bar" #}</div>

Commenting out a block of toffee

In toffee mode, you can comment out a region with {## and ##}.

<div>
 I don't want to output this anymore...
 {##
     <p>An ode to Ruby on Rails</p>
     <p>#{partial 'ode.toffee'}</p>
 ##}
</div>

Escaping

In your CoffeeScript, the print function lets you print the raw value of a variable:

{#
  danger_code = "<script>alert('Eat a bag.');</script>"
  print danger_code
#}

But in toffee mode, #{some_expression} output is escaped intelligently by default:

<!-- escapes the HTML -->
<p>#{danger_code}</p>

You can control the escaping, but here are the defaults:

  • if it's a string or scalar, it is escaped for HTML safety.
  • it's an array or object, it is converted to JSON.

Custom Escaping

You can bypass the above rules.

  • #{json foo}: this outputs foo as JSON.
  • #{raw foo}: this outputs foo in raw text.
  • #{html foo}: this outputs foo, escaped as HTML. For a scalar, it's the same as #{foo}, but it's available in case you (1) override the default escaping or (2) turn off auto-escaping (both explained below).
  • #{partial "foo.toffee"} and #{snippet "foo.toffee"}: unescaped, since you don't want to escape your own templates

When any of the functions mentioned above are leftmost in a #{} token in toffee mode, their output is left untouched by the built in escape function.

These functions are also available to you in coffee mode.

<p>
    Want to read some JSON, human?
    {#
       foo = [1,2,3, {bar: "none"}]
       foo_as_json_as_html = html json foo
       print foo_as_json_as_html
    #}
</p>

Note! if you pass a variable to the template called json, raw, or html, Toffee won't create these helper functions, which would override your vars. In this case, you can access the escape functions through their official titles, __toffee.raw, etc.

Overriding the default escape:

  • If you pass a variable to your template called escape, this will be used as the default escape. In toffee mode, everything inside #{} that isn't subject to an above-mentioned exception will go through your escape function.

Turning off autoescaping entirely:

  • If you set autoEscape: false when creating the engine, the default will be raw across your project. (See more on that below under Express 3.x settings.)
  • Alternatively, you could pass the var escape: (x) -> x to turn off escaping for a given template.

Common Questions

How does it compare to eco?

Eco is another CoffeeScript templating language and inspiration for Toffee. The syntaxes are pretty different, so pick the one you prefer.

One big Toffee advantage: multiple lines of CoffeeScript just look like CoffeeScript. Compare:

ECO

<% if @projects.length: %>
  <% for project in @projects: %>
    <% if project.is_active: %>
      <p><%= project.name %> | <%= project.description %></p>
    <% end %>
  <% end %>
<% end %>

TOFFEE

{#
   if projects.length
    for project in @projects
      if project.is_active {:
        <p>#{project.name} | #{project.description}</p>
      :}
#}

With Toffee's syntax, brackets enclose regions not directives, so your editor will let you collapse and expand sections of code. And if you click on one of the brackets in most editors, it will highlight the matching bracket.

Does it cache templates?

In Express 2.0, that's up to Express. When used in Express 3.0, Toffee asynchronously monitors known templates and recompiles them in the background when necessary. So you don't need to restart your production webserver whenever you edit a template.

Does it find line numbers in errors?

Yes, Toffee does a very good job of that. There are 3 possible places you can hit an error in Toffee:

  • in the language itself, say a parse error
  • in the CoffeeScript, preventing it from compiling to JS
  • runtime, in the final JS

Stack traces are converted to lines in Toffee and show you where the problem is. By default when Toffee hits an error it replies with some pretty-printed HTML showing you the problem. This can be overridden, as explained below in the Express 3.0 section.

Does it support partials? (a.k.a includes)

Yes. In Express 2.0, Express itself is responsible for including other files, and they call this system "partials." In Express 3.0 and in the browser, Toffee defines the partial function, and it works as you'd expect.

<div>#{partial '../foo/bar.toffee', name: "Chris"}</div>

Inside a region of CoffeeScript, you can print or capture the result of a partial.

<div>
{#
   if session
      print partial 'user_menu.toffee', info: session.info
   else
      print partial 'guest_menu.toffee'
#}
</div>

Like Express's partial function, Toffee's function passes all available vars to the child template. For example, in the above code, session would also be available in the user_menu.toffee file. If you don't want this scoping, use Toffee's snippet function, which sandboxes it:

{#
   if session
      print partial 'user.toffee', info: session.info # session will also be passed
      print snippet 'user.toffee', info: session.info # session will not be passed
#}

Does it support layout?

Yes, this works in Express 3.0, emulating the Express 2.0 way. If you publish a file foo.toffee and pass a layout filename to it as a var, foo.toffee is rendered, and the results are put into a var called body. Then your layout is rendered, using all your vars plus the new body var.

Installation & Usage

npm install -g toffee

In Express 3.x to make it your default engine:

app.set 'view engine', 'toffee'

In Express 3.x to use it just for .toffee files:

toffee = require 'toffee'
app.engine 'toffee', toffee.__express

Express 2.x:

toffee      = require 'toffee'
app.register '.toffee', toffee

express 3.x options

Pretty-print errors

Express's default error page is great for stack traces but not so great for pretty-printing template errors. So by default, when Toffee hits any kind of error (in your templates, in your CoffeeScript, or even at runtime), it fakes an okay result by returning some pretty HTML showing the error. If you don't like this - say you want to catch render errors - you can turn it off.

toffee = require 'toffee'
toffee.expressEngine.prettyPrintErrors = false

Turning off auto-escaping for HTML

By default, Toffee escapes #{} output for HTML. You can turn this off in your engine with:

toffee = require 'toffee'
toffee.expressEngine.autoEscape = false

Browser Usage! (Compiling your .toffee files)

You can compile an entire project of .toffee files easily into a .js file. Even partials work with the same path-based syntax.

Please see Browser Usage in the wiki, as the toffee command line program has a lot of options.

contributing & asking for fixes.

If you have a problem with Toffee let me know, and I'll fix it ASAP.

Also, I'm likely to accept good pull requests.

If you'd like to edit code for this project, note that you should always edit the .coffee files, as the .js files are generated automatically by building.

To build

> cake build

To make sure you didn't break something

> coffee tests/run_cases.coffee
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