node-sass

What is node-sass?

The node-sass npm package is a library that allows you to natively compile .scss files to CSS at incredible speed and automatically via a connect middleware. It provides a binding for Node.js to the Sass engine, which is written in C++ and allows for the translation of SCSS or SASS syntax into standard CSS that browsers can understand.

What are node-sass's main functionalities?

Compiling SCSS to CSS

This feature allows you to compile .scss files into .css files. The 'render' method takes an options object and a callback function. The options object specifies the input and output paths for the SCSS and CSS files, respectively. The callback is invoked after the compilation process, and you can handle the result or error accordingly.

const sass = require('node-sass');
sass.render({
  file: 'path/to/input.scss',
  outFile: 'path/to/output.css'
}, function(error, result) { // Node-style callback from v3.0.0 onwards
  if(!error){
    // No errors during the compilation, write this result on the disk
    fs.writeFile('path/to/output.css', result.css, function(err){
      if(!err){
        //file written on disk
      }
    });
  }
});

Watching files or directories

This feature allows you to watch .scss files or directories for changes and automatically recompile them to CSS when a change is detected. The example uses 'chokidar', an external library for watching files, to listen for changes on the specified SCSS file and then uses node-sass to compile the file to CSS.

const sass = require('node-sass');
const chokidar = require('chokidar');

chokidar.watch('path/to/input.scss').on('change', () => {
  sass.render({
    file: 'path/to/input.scss',
    outFile: 'path/to/output.css'
  }, function(error, result) {
    if (!error) {
      fs.writeFile('path/to/output.css', result.css, function(err){
        if(!err){
          console.log('SCSS file updated.');
        }
      });
    }
  });
});

Command Line Interface (CLI) usage

node-sass provides a CLI for compiling SCSS files to CSS directly from the command line. In this example, the '--output-style' option is used to specify the CSS output format (compressed in this case), '-o' is used to define the output directory for the compiled CSS, and the last argument is the input directory containing the SCSS files.

node-sass --output-style compressed -o dist/css src/scss

Other packages similar to node-sass

sass

The 'sass' package is the primary implementation of Sass, which is written in Dart. It provides the same core functionality as node-sass but does not rely on a native C++ binding, making it more portable and easier to install across different environments. It is also the package recommended by the Sass team as node-sass has been deprecated.

postcss

PostCSS is a tool for transforming CSS with JavaScript plugins. While it is not a direct replacement for node-sass, it can be used with plugins like 'precss' to provide similar SCSS-like syntax and features. PostCSS is highly extensible and can be integrated with a large number of plugins to extend its capabilities beyond what node-sass offers.

less

Less is a backward-compatible language extension for CSS. It is similar to SCSS in terms of features like variables, mixins, and nesting, but it has its own syntax and compiles to CSS using the Less compiler. While it serves a similar purpose to node-sass, it is a different preprocessor language with its own community and ecosystem.

stylus

Stylus is a preprocessor that serves as an alternative to SCSS. It offers a flexible syntax with optional colons, semicolons, and braces, and provides powerful features like variable interpolation and functions. Stylus can be seen as a more expressive, but less widely adopted, alternative to node-sass.

README

node-sass

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: https://npmjs.org/package/node-sass

Follow @nodesass on twitter for release updates: https://twitter.com/nodesass

Reporting Sass compilation and syntax issues

The libsass library is not currently at feature parity with the 3.2 Ruby Gem that most Sass users will use, and has little-to-no support for 3.3 syntax. While we try our best to maintain feature parity with libsass, we can not enable features that have not been implemented in libsass yet.

If you'd like to see what features are still upcoming in libsass, Jo Liss has written a blog post on the subject.

Please check for issues on the libsass repo (as there is a good chance that it may already be an issue there for it), and otherwise create a new issue there.

If this project is missing an API or command line flag that has been added to libsass, then please open an issue here. We will then look at updating our libsass submodule and create a new release. You can help us create the new release by rebuilding binaries, and then creating a pull request to the node-sass-binaries repo.

Install

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.

Usage

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

Options

The API for using node-sass has changed, so that now there is only one variable - an options hash. Some of these options are optional, and in some circumstances some are mandatory.

file

file is a String of the path to an scss file for libsass to render. One of this or data options are required, for both render and renderSync.

data

data is a String containing the scss to be rendered by libsass. One of this or file options are required, for both render and renderSync. It is recommended that you use the includePaths option in conjunction with this, as otherwise libsass may have trouble finding files imported via the @import directive.

success

success is a Function to be called upon successful rendering of the scss to css. This option is required but only for the render function. If provided to renderSync it will be ignored.

The callback function is passed a results object, containing the following keys:

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

error

error is a Function to be called upon occurrence of an error when rendering the scss to css. This option is optional, and only applies to the render function. If provided to renderSync it will be ignored.

importer (starting from v2)

importer is a Function to be called when libsass parser encounters the import directive. If present, libsass will call node-sass and let the user change file, data or both during the compilation. This option is optional, and applies to both render and renderSync functions. Also, it can either return object of form {file:'..', contents: '..'} or send it back via done({}). Note in renderSync or render, there is no restriction imposed on using done() callback or return statement (dispite of the asnchrony difference).

includePaths

includePaths is an Array of path Strings to look for any @imported files. It is recommended that you use this option if you are using the data option and have any @import directives, as otherwise libsass may not find your depended-on files.

imagePath

imagePath is a String that represents the public image path. When using the image-url() function in a stylesheet, this path will be prepended to the path you supply. eg. Given an imagePath of /path/to/images, background-image: image-url('image.png') will compile to background-image: url("/path/to/images/image.png")

indentedSyntax

indentedSyntax is a Boolean flag to determine if Sass Indented Syntax should be used to parse provided string or a file.

omitSourceMapUrl

omitSourceMapUrl is a Boolean flag to determine whether to include sourceMappingURL comment in the output file.

outFile

outFile specifies where the CSS will be saved. This option does not actually output a file, but is used as input for generating a source map.

outputStyle

outputStyle is a String to determine how the final CSS should be rendered. Its value should be one of 'nested' or 'compressed'. Node-sass defaults to 'nested'. ['expanded' and 'compact' are not currently supported by libsass]

precision

precision is a Number that will be 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.

sourceComments

sourceComments is a Boolean flag to determine what debug information is included in the output file.

sourceMap

You must define this option as well as outFile in order to generate a source map. If it is set to true, the source map will be generated at the path provided in the outFile option. If set to a path (String), the source map will be generated at the provided path.

sourceMapEmbed

sourceMapEmbed is a Boolean flag to determine whether to embed sourceMappingUrl as data URI.

sourceMapContents

sourceMapContents is a Boolean flag to determine whether to include contents in maps.

Examples

var sass = require('node-sass');
sass.render({
	file: '/path/to/myFile.scss',
	data: 'body{background:blue; a{color:black;}}',
	success: function(result) {
		// result is an object: v2 change
        console.log(result.css);
        console.log(result.stats);
        console.log(result.map)
	},
	error: function(error) {
		// error is an object: v2 change
		console.log(error.message);
		console.log(error.code);
		console.log(error.line);
		console.log(error.column); // new in v2
	},
	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.
		someAsyncFunction(url, prev, function(result){
			done({
				file: result.path, // only one of them is required, see section Sepcial Behaviours.
				contents: result.data
			});
		});
		// OR
		var result = someSyncFunction(url, prev);
		return {file: result.path, contents: result.data};
	},
	includePaths: [ 'lib/', 'mod/' ],
	outputStyle: 'compressed'
});
// 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.
		someAsyncFunction(url, prev, function(result){
			done({
				file: result.path, // only one of them is required, see section Sepcial Behaviours.
				contents: result.data
			});
		});
		// OR
		var result = someSyncFunction(url, prev);
		return {file: result.path, contents: result.data};
	},
}));

console.log(result.css);
console.log(result.map);
console.log(result.stats);

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 change)

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

require('node-sass').info();

// outputs something like:
// node-sass version: 2.0.0-beta
// libsass version: 3.1.0-beta

Integrations

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

Brackets extension

@jasonsanjose has created a Brackets extension based on node-sass: https://github.com/jasonsanjose/brackets-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: https://github.com/brunch/sass-brunch

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: https://github.com/jking90/docpad-plugin-nodesass

Duo.js extension

@stephenway has created an extension that transpiles Sass to CSS using node-sass with duo.js https://github.com/duojs/sass

Grunt extension

@sindresorhus has created a set of grunt tasks based on node-sass: https://github.com/sindresorhus/grunt-sass

Gulp extension

@dlmanning has created a gulp sass plugin based on node-sass: https://github.com/dlmanning/gulp-sass

Harp

@sintaxi’s Harp web server implicitly compiles .scss files using node-sass: https://github.com/sintaxi/harp

Metalsmith plugin

@stevenschobert has created a metalsmith plugin based on node-sass: https://github.com/stevenschobert/metalsmith-sass

Meteor plugin

@fourseven has created a meteor plugin based on node-sass: https://github.com/fourseven/meteor-scss

Mimosa module

@dbashford has created a Mimosa module for sass which includes node-sass: https://github.com/dbashford/mimosa-sass

Example App

There is also an example connect app here: https://github.com/andrew/node-sass-example

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 https://github.com/sass/node-sass.git
cd node-sass
git submodule update --init --recursive
npm install
npm install -g node-gyp
node-gyp rebuild  # to make debug release, use -d switch

Workaround for node v0.11.13 v0.11.14

Follow the steps above, but comment out this line in lib/index.js before the npm install step. Then uncomment it back again, and continue with the rest of the steps (see issue #563).

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.

Usage

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

Options:

    -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)
    --output-style             CSS output style (nested|expanded|compact|compressed)
    --source-comments          Include debug info in output
    --source-map               Emit source map
    --source-map-embed         Embed sourceMappingUrl as data URI
    --source-map-contents      Embed include contents in map
    --include-path             Path to look for imported files
    --image-path               Path to prepend when using the `image-url()` helper
    --precision                The amount of precision allowed in decimal numbers
    --stdout                   Print the resulting CSS to stdout
    --importer                 Path to custom importer
    --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.

Maintainers

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

• Adeel Mujahid - Project Lead (Github / Twitter)
• Andrew Nesbitt (Github / Twitter)
• Dean Mao (Github / Twitter)
• Brett Wilkins (Github / Twitter)
• Keith Cirkel (Github / Twitter)
• Laurent Goderre (Github / Twitter)
• Nick Schonning (Github / Twitter)
• Adam Yeats (Github / Twitter)

Contributors

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

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