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Babel

Babel

Babel puts a soft cushion between a web application and the many cool new file formats developed for use with node.js such as CoffeeScript, SASS, and Jade. With Babel, you will be able to seamlessly load from many different types of files without having to worry about the many APIs involved.

Features

  • Easily load stylesheets, data, templates, and scripts from many popular formats
  • Never worry about format lock-in
  • Experiment with different formats with ease

Installation

To install babel, use npm

npm install babel

Then Babel can easily be included into any node.js project

Babel = require("babel");

Methods

Babel.template(file, callback)

Load and convert a template file into a JavaScript function.

A template is a snippet of HTML which can be used many times with different values.

file is an absolute path to the template file and callback is a function which will be called as callback(err, template) after the file is loaded and converted.

The template function returned to callback can be used to render the template with a values object and a context object by calling template.call(context, values).

Example

If you had a embedded CoffeeScript file

<h1><%= @greeting %> <%= planet %></h1>

you could load it with

Babyl.template("hello.eco", function(err, render) {
	// ...
});

and then render it with

var context = { greeting: "Hello" };
var values = { planet: "world" };

var output = render.call(context, values);

Now, output will equal <h1>hello world</h1>

Supported Formats

Babel.data(file, callback)

Load and convert a data file into a JavaScript object

A data file contains a serialized JavaScript object. Since these files are static (you cannot easily write to them) they are typically used for storing settings or unchanging data.

file is an absolute path to the data file and callback is a function which will be invoked as callback(err, data) after the data is loaded and converted.

The data object returned to callback is a JavaScript object.

Example

If you had a JSON file

{
	"username": "root",
	"password": "asdf"
}

you could load it with

Babyl.data("accounts.json", function(err, data) {
	// ...
});

now data will equal { username: "root", "password": "asdf" }

Supported Formats

Babel.script(file, callback)

Load and convert a script into a JavaScript function.

A script is a file containing code. This code is compiled into a JavaScript function which can be run multiple times with different values and contexts.

file is an absolute path to the script and callback is a function which will be invoked as callback(err, script).

The script function returned to callback can be used to run the script with a values object and a context object by calling script.call(context, values).

Example

If you had a CoffeeScript file

x for x in [@min..max] by 2

you could load it with

Babyl.data("evens.coffee", function(err, script) {
	// ...
});

and run the script with

var evens = script.call({ min: 0 }, { max: 10 });

now evens will equal [ 0, 2, 4, 6, 8, 10 ]

Supported Formats

  • JavaScript (*.js)
  • CoffeeScript (*.coffee)

Babel.stylesheet(file, callback)

Load a convert a stylesheet into a string of CSS rules.

A stylesheet is any file that defines the visual appearance of a HTML document that can be translated into CSS.

file is an absolute path to the stylesheet file and callback is a function which will be invoked as callback(err, css).

The css string contains valid CSS rules ready to be inserted into the document

Example

If you had a LESS stylesheet

.blog-post {
	h2 { color: red; }
}

you could load it with

Babyl.data("blog.scss", function(err, css) {
	// ...
});

now css will equal ".blog-post h2 { color: red }"

Supported Formats

  • CSS (*.css)
  • LESS (*.less)
  • SCSS (*.scss)
  • Stylus (*.styl)

Babel.dir(dir, iterator, callback)

Load all files in a directory in one step.

Call iterator for each file in dir as iterator(file, callback). The iterator can then asynchronously load the file and call callback with the result. (note: this is not the same callback as is passed to Babel.dir). All results are gathered into a JavaScript object as { <file basename>: <result>, ... } and passed to callback

This method works very well with all Babel load methods -- just use them as the iterator

Babel.dir(dir, Babel.template, function(err, templates) { ... }

Example

If you you have a folder full of templates

stylesheets/
	body.html
	post.jade
	header.eco
	footer.ejs

you can load all templates in one step with

Babel.dir(dir, Babel.template, function(err, templates) {
	// ...
});

templates will equal

{
	body: function(values) { ... },
	post: function(values) { ... },
	header: function(values) { ... },
	footer: function(values) { ... }
}

Creating Translators

Translators contain the instructions for converting a specific file type (defined by the file extension) into a standardized data structure.

A translator is function invoked by Babel as translator(source, callback), where source is the raw contents of the file being translated. This function is run asynchronously to convert the source into a data structure (as defined per file type in the sections below).

Translators are located at ./translators/<type>/<extension>.coffee where <extension> refers to the file extension a file of that type would have. For example, the JSON data translator is located at translators/data/json.coffee. The translator function should be placed into module.exports.

Data

Data translators should return a JavaScript object representation of the source.

Script

A script translator returns a function of the signature script(values).

values is an object to be used as the local scope when running the script (presumably inside a with(values) { ... } block). This function should also support being run as script.call(context, values).

Values returned in the script's execution by return statements should be returned from the script(values) function.

Stylesheet

A stylesheet translator should return a string of W3C valid CSS rules.

Template

A template translator should return a function of the signature render(values)

values is an object to be used as the local scope when rendering the template (presumably inside a with(values) { ... } block). This function should also support being run as template.call(context, values).

The template should still work after being passed through template.toString()