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:rainbow: Node.js bindings to libsass
JavaScript C++ Python

Merge pull request #817 from am11/master

Importer: Allows importer to return error
latest commit 40d6f13801
@am11 am11 authored


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Node-sass is a library that provides binding for Node.js to libsass, the C version of the popular stylesheet preprocessor, Sass.

It allows you to natively compile .scss files to css at incredible speed and automatically via a connect middleware.

Find it on npm:

Follow @nodesass on twitter for release updates:


npm install node-sass

Some users have reported issues installing on Ubuntu due to node being registered to another package. Follow the official NodeJS docs to install NodeJS so that #!/usr/bin/env node correctly resolved.

Compiling versions 0.9.4 and above on Windows machines requires Visual Studio 2013 WD. If you have multiple VS versions, use npm install with the --msvs_version=2013 flag also use this flag when rebuilding the module with node-gyp or nw-gyp.


var sass = require('node-sass');
  file: scss_filename,
  [, options..]
}, function(err, result) { /*...*/ });
// OR
var result = sass.renderSync({
  data: scss_content
  [, options..]



Type: String | null Default: null Special: file or data must be specified

Path to a file for libsass to render.


Type: String | null Default: null Special: file or data must be specified

A string to pass to libsass to render. It is recommended that you use includePaths in conjunction with this so that libsass can find files when using the @import directive.

importer (>= v2.0.0)

Type: Function signature function(url, prev, done) Default: undefined

Function Parameters and Information:

  • url (String) - the path in import as-is, which libsass encountered
  • prev (String) - the previously resolved path
  • done (Function) - a callback function to invoke on async completion, takes an object literal containing
    • file (String) - an alternate path for libsass to use OR
    • contents (String) - the imported contents (for example, read from memory or the file system)

Handles when libsass encounters the @import directive. A custom importer allows extension of the libsass engine in both a synchronous and asynchronous manner. In both cases, the goal is to either return or call done() with an object literal. Depending on the value of the object literal, one of two things will happen.

When returning or calling done() with { file: "String" }, the new file path will be assumed for the @import. It's recommended to be mindful of the value of prev in instances where relative path resolution may be required.

When returning or calling done() with { contents: "String" }, the string value will be used as if the file was read in through an external source.

Starting from v3.0.0, this refers to a contextual scope for the immediate run of sass.render or sass.renderSync

functions (>= v3.0.0)

functions is an Object that holds a collection of custom functions that may be invoked by the sass files being compiled. They may take zero or more input parameters and must return a value either synchronously (return ...;) or asynchronously (done();). Those parameters will be instances of one of the constructors contained in the require('node-sass').types hash. The return value must be of one of these types as well. See the list of available types below:

types.Number(value [, unit = ""])

  • getValue()/ setValue(value) : gets / sets the numerical portion of the number
  • getUnit() / setUnit(unit) : gets / sets the unit portion of the number


  • getValue() / setValue(value) : gets / sets the enclosed string

types.Color(r, g, b [, a = 1.0]) or types.Color(argb)

  • getR() / setR(value) : red component (integer from 0 to 255)
  • getG() / setG(value) : green component (integer from 0 to 255)
  • getB() / setB(value) : blue component (integer from 0 to 255)
  • getA() / setA(value) : alpha component (number from 0 to 1.0)


var Color = require('node-sass').types.Color,
  c1 = new Color(255, 0, 0),
  c2 = new Color(0xff0088cc);


  • getValue() : gets the enclosed boolean
  • types.Boolean.TRUE : Singleton instance of types.Boolean that holds "true"
  • types.Boolean.FALSE : Singleton instance of types.Boolean that holds "false"

types.List(length [, commaSeparator = true])

  • getValue(index) / setValue(index, value) : value must itself be an instance of one of the constructors in sass.types.
  • getSeparator() / setSeparator(isComma) : whether to use commas as a separator
  • getLength()


  • getKey(index) / setKey(index, value)
  • getValue(index) / setValue(index, value)
  • getLength()


  • types.Null.NULL : Singleton instance of types.Null.


  data: '#{headings(2,5)} { color: #08c; }',
  functions: {
    'headings($from: 0, $to: 6)': function(from, to) {
      var i, f = from.getValue(), t = to.getValue(),
          list = new sass.types.List(t - f + 1);

      for (i = f; i <= t; i++) {
        list.setValue(i - f, new sass.types.String('h' + i));

      return list;


Type: Array<String> Default: []

An array of paths that libsass can look in to attempt to resolve your @import declarations. When using data, it is recommended that you use this.


Type: Boolean Default: false

true values enable Sass Indented Syntax for parsing the data string or file.

indentType (>= v3.0.0)

Type: String Default: space

Used to determine whether to use space or tab character for indentation.

indentWidth (>= v3.0.0)

Type: Number Default: 2 Maximum: 10

Used to determine the number of spaces or tabs to be used for indentation.

linefeed (>= v3.0.0)

Type: String Default: lf

Used to determine whether to use cr, crlf, lf or lfcr sequence for line break.


Type: Boolean Default: false Special: When using this, you should also specify outFile to avoid unexpected behavior.

true values disable the inclusion of source map information in the output file.


Type: String | null Default: null Special: Required when sourceMap is a truthy value

Specify the intended location of the output file. Strongly recommended when outputting source maps so that they can properly refer back to their intended files.


Type: String Default: nested Values: nested, compressed

Determines the output format of the final CSS style. ('expanded' and 'compact' are not currently supported by libsass, but are planned in a future version.)


Type: Integer Default: 5

Used to determine how many digits after the decimal will be allowed. For instance, if you had a decimal number of 1.23456789 and a precision of 5, the result will be 1.23457 in the final CSS.


Type: Boolean Default: false

true enables additional debugging information in the output file as CSS comments


Type: Boolean | String | undefined Default: undefined Special: Setting the sourceMap option requires also setting the outFile option

Enables the outputting of a source map during render and renderSync. When sourceMap === true, the value of outFile is used as the target output location for the source map. When typeof sourceMap === "String", the value of sourceMap will be used as the writing location for the file.


Type: Boolean Default: false

true includes the contents in the source map information


Type: Boolean Default: false

true embeds the source map as a data URI


Type: String Default: undefined

the value will be emitted as sourceRoot in the source map information

render Callback (>= v3.0.0)

node-sass supports standard node style asynchronous callbacks with the signature of function(err, result). In error conditions, the error argument is populated with the error object. In success conditions, the result object is populated with an object describing the result of the render call.

Error Object

  • message (String) - The error message.
  • line (Number) - The line number of error.
  • column (Number) - The column number of error.
  • status (Number) - The status code.
  • file (String) - The filename of error. In case file option was not set (in favour of data), this will reflect the value stdin.

Result Object

  • css (Buffer) - The compiled CSS. Write this to a file, or serve it out as needed.
  • map (Buffer) - The source map
  • stats (Object) - An object containing information about the compile. It contains the following keys:
    • entry (String) - The path to the scss file, or data if the source was not a file
    • start (Number) - before the compilation
    • end (Number) - after the compilation
    • duration (Number) - end - start
    • includedFiles (Array) - Absolute paths to all related scss files in no particular order.


var sass = require('node-sass');
  file: '/path/to/myFile.scss',
  data: 'body{background:blue; a{color:black;}}',
  importer: function(url, prev, done) {
    // url is the path in import as is, which libsass encountered.
    // prev is the previously resolved path.
    // done is an optional callback, either consume it or return value synchronously.
    // this.options contains this options hash, this.callback contains the node-style callback
    someAsyncFunction(url, prev, function(result){
        file: result.path, // only one of them is required, see section Sepcial Behaviours.
    // OR
    var result = someSyncFunction(url, prev);
    return {file: result.path, contents:};
  includePaths: [ 'lib/', 'mod/' ],
  outputStyle: 'compressed'
}, function(error, result) { // node-style callback from v3.0.0 onwards
  if (error) {
    console.log(error.status); // used to be "code" in v2x and below
  else {


    // or better
    console.log(JSON.stringify(; // note, JSON.stringify accepts Buffer too
// OR
var result = sass.renderSync({
  file: '/path/to/file.scss',
  data: 'body{background:blue; a{color:black;}}',
  outputStyle: 'compressed',
  outFile: '/to/my/output.css',
  sourceMap: true, // or an absolute or relative (to outFile) path
  importer: function(url, prev, done) {
    // url is the path in import as is, which libsass encountered.
    // prev is the previously resolved path.
    // done is an optional callback, either consume it or return value synchronously.
    // this.options contains this options hash
    someAsyncFunction(url, prev, function(result){
        file: result.path, // only one of them is required, see section Sepcial Behaviours.
    // OR
    var result = someSyncFunction(url, prev);
    return {file: result.path, contents:};


Special behaviours

  • In the case that both file and data options are set, node-sass will give precedence to data and use file to calculate paths in sourcemaps.

Version information (>= v2.0.0)

Both node-sass and libsass version info is now present in package.json and is exposed via info method:

var sass = require('node-sass');


  it will output something like:

  node-sass       2.0.1   (Wrapper)       [JavaScript]
  libsass         3.1.0   (Sass Compiler) [C/C++]


Listing of community uses of node-sass in build tools and frameworks.

Brackets extension

@jasonsanjose has created a Brackets extension based on node-sass: When editing Sass files, the extension compiles changes on save. The extension also integrates with Live Preview to show Sass changes in the browser without saving or compiling.

Brunch plugin

Brunch's official sass plugin uses node-sass by default, and automatically falls back to ruby if use of Compass is detected:

Connect/Express middleware

Recompile .scss files automatically for connect and express based http servers.

This functionality has been moved to node-sass-middleware in node-sass v1.0.0

DocPad Plugin

@jking90 wrote a DocPad plugin that compiles .scss files using node-sass:

Duo.js extension

@stephenway has created an extension that transpiles Sass to CSS using node-sass with duo.js

Grunt extension

@sindresorhus has created a set of grunt tasks based on node-sass:

Gulp extension

@dlmanning has created a gulp sass plugin based on node-sass:


@sintaxi’s Harp web server implicitly compiles .scss files using node-sass:

Metalsmith plugin

@stevenschobert has created a metalsmith plugin based on node-sass:

Meteor plugin

@fourseven has created a meteor plugin based on node-sass:

Mimosa module

@dbashford has created a Mimosa module for sass which includes node-sass:

Example App

There is also an example connect app here:

Rebuilding binaries

Node-sass includes pre-compiled binaries for popular platforms, to add a binary for your platform follow these steps:

Check out the project:

git clone --recursive
cd node-sass
git submodule update --init --recursive
npm install
node scripts/build -f  # use -d switch for debug release
# if succeeded, it will generate and move
# the binary in vendor directory.

Command Line Interface

The interface for command-line usage is fairly simplistic at this stage, as seen in the following usage section.

Output will be saved with the same name as input SASS file into the current working directory if it's omitted.


node-sass [options] <input.scss> [output.css] cat <input.scss> | node-sass > output.css


    -w, --watch                Watch a directory or file
    -r, --recursive            Recursively watch directories or files
    -o, --output               Output directory
    -x, --omit-source-map-url  Omit source map URL comment from output
    -i, --indented-syntax      Treat data from stdin as sass code (versus scss)
    -v, --version              Prints version info
    --output-style             CSS output style (nested | expanded | compact | compressed)
    --indent-type              Indent type for output CSS (space | tab)
    --indent-width             Indent width; number of spaces or tabs (maximum value: 10)
    --linefeed                 Linefeed style (cr | crlf | lf | lfcr)
    --source-comments          Include debug info in output
    --source-map               Emit source map
    --source-map-contents      Embed include contents in map
    --source-map-embed         Embed sourceMappingUrl as data URI
    --source-map-root          Base path, will be emitted in source-map as is
    --include-path             Path to look for imported files
    --precision                The amount of precision allowed in decimal numbers
    --importer                 Path to .js file containing custom importer
    --functions                Path to .js file containing custom functions
    --help                     Print usage info

Note --importer takes the (absolute or relative to pwd) path to a js file, which needs to have a default module.exports set to the importer function. See our test fixtures for example.

Post-install Build

Install runs only two Mocha tests to see if your machine can use the pre-built libsass which will save some time during install. If any tests fail it will build from source.


This module is brought to you and maintained by the following people:


We <3 our contributors! A special thanks to all those who have clocked in some dev time on this project, we really appreciate your hard work. You can find a full list of those people here.

Note on Patches/Pull Requests

  • Fork the project.
  • Make your feature addition or bug fix.
  • Add documentation if necessary.
  • Add tests for it. This is important so I don't break it in a future version unintentionally.
  • Send a pull request. Bonus points for topic branches.


Copyright (c) 2015 Andrew Nesbitt. See LICENSE for details.

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