node-sass
Advanced tools
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.
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/scssThe '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 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 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 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.
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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: https://www.npmjs.com/package/node-sass
Follow @nodesass on twitter for release updates: https://twitter.com/nodesass
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.
Having installation troubles? Check out our Troubleshooting guide.
var sass = require('node-sass');
sass.render({
file: scss_filename,
[, options..]
}, function(err, result) { /*...*/ });
// OR
var result = sass.renderSync({
data: scss_content
[, options..]
});
Type: String
Default: null
Special: file or data must be specified
Path to a file for LibSass to render.
Type: String
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.
This is an experimental LibSass feature. Use with caution.
Type: Function | Function[] signature function(url, prev, done)
Default: undefined
Function Parameters and Information:
url (String) - the path in import as-is, which LibSass encounteredprev (String) - the previously resolved pathdone (Function) - a callback function to invoke on async completion, takes an object literal containing
file (String) - an alternate path for LibSass to use ORcontents (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
importers can return error and LibSass will emit that error in response. For instance:
done(new Error('doesn\'t exist!'));
// or return synchornously
return new Error('nothing to do here');
importer can be an array of functions, which will be called by LibSass in the order of their occurrence in array. This helps user specify special importer for particular kind of path (filesystem, http). If an importer does not want to handle a particular path, it should return null. See functions section for more details on Sass types.
This is an experimental LibSass feature. Use with caution.
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:
getValue()/ setValue(value) : gets / sets the numerical portion of the numbergetUnit() / setUnit(unit) : gets / sets the unit portion of the numbergetValue() / setValue(value) : gets / sets the enclosed stringgetR() / 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)Example:
var Color = require('node-sass').types.Color,
c1 = new Color(255, 0, 0),
c2 = new Color(0xff0088cc);
getValue() : gets the enclosed booleantypes.Boolean.TRUE : Singleton instance of types.Boolean that holds "true"types.Boolean.FALSE : Singleton instance of types.Boolean that holds "false"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 separatorgetLength()getKey(index) / setKey(index, value)getValue(index) / setValue(index, value)getLength()types.Null.NULL : Singleton instance of types.Null.sass.renderSync({
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.
Note: node-sass/libsass will compile a mixed library of scss and indented syntax (.sass) files with the Default setting (false) as long as .sass and .scss extensions are used in filenames.
Type: String
Default: space
Used to determine whether to use space or tab character for indentation.
Type: Number
Default: 2
Maximum: 10
Used to determine the number of spaces or tabs to be used for indentation.
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.
Attention enabling this option will not write the file on disk for you, it's for internal reference purpose only (to generate the map for example).
Example on how to write it on the disk
sass.render({
...
outFile: yourPathTotheFile,
}, 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(yourPathTotheFile, result.css, function(err){
if(!err){
//file written on disk
}
});
}
});
});
Type: String
Default: nested
Values: nested, expanded, compact, compressed
Determines the output format of the final CSS style.
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 the line number and file where a selector is defined to be emitted into the compiled CSS as a comment. Useful for debugging, especially when using imports and mixins.
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.
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.css (Buffer) - The compiled CSS. Write this to a file, or serve it out as needed.map (Buffer) - The source mapstats (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 filestart (Number) - Date.now() before the compilationend (Number) - Date.now() after the compilationduration (Number) - end - startincludedFiles (Array) - Absolute paths to all related scss files in no particular order.var sass = require('node-sass');
sass.render({
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){
done({
file: result.path, // only one of them is required, see section Special Behaviours.
contents: result.data
});
});
// OR
var result = someSyncFunction(url, prev);
return {file: result.path, contents: result.data};
},
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
console.log(error.column);
console.log(error.message);
console.log(error.line);
}
else {
console.log(result.css.toString());
console.log(result.stats);
console.log(result.map.toString());
// or better
console.log(JSON.stringify(result.map)); // 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){
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);
file and data options are set, node-sass will give precedence to data and use file to calculate paths in sourcemaps.Both node-sass and libsass version info is now exposed via the info method:
var sass = require('node-sass');
console.log(sass.info);
/*
it will output something like:
node-sass 2.0.1 (Wrapper) [JavaScript]
libsass 3.1.0 (Sass Compiler) [C/C++]
*/
Since node-sass >=v3.0.0 LibSass version is determined at run time.
Listing of community uses of node-sass in build tools and frameworks.
@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'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
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
@jking90 wrote a DocPad plugin that compiles .scss files using node-sass: https://github.com/jking90/docpad-plugin-nodesass
@stephenway has created an extension that transpiles Sass to CSS using node-sass with duo.js https://github.com/duojs/sass
@sindresorhus has created a set of grunt tasks based on node-sass: https://github.com/sindresorhus/grunt-sass
@dlmanning has created a gulp sass plugin based on node-sass: https://github.com/dlmanning/gulp-sass
@sintaxi’s Harp web server implicitly compiles .scss files using node-sass: https://github.com/sintaxi/harp
@stevenschobert has created a metalsmith plugin based on node-sass: https://github.com/stevenschobert/metalsmith-sass
@fourseven has created a meteor plugin based on node-sass: https://github.com/fourseven/meteor-scss
@dbashford has created a Mimosa module for sass which includes node-sass: https://github.com/dbashford/mimosa-sass
There is also an example connect app here: https://github.com/andrew/node-sass-example
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
node scripts/build -f # use -d switch for debug release
# if succeeded, it will generate and move
# the binary in vendor directory.
The interface for command-line usage is fairly simplistic at this stage, as seen in the following usage section.
Output will be sent to stdout if the --output flag is omitted.
node-sass [options] <input> [output]
Or:
cat <input> | node-sass > output
Example:
node-sass src/style.scss dest/style.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)
-q, --quiet Suppress log output except on error
-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
--follow Follow symlinked directories
--precision The amount of precision allowed in decimal numbers
--error-bell Output a bell character on errors
--importer Path to .js file containing custom importer
--functions Path to .js file containing custom functions
--help Print usage info
The input can be either a single .scss or .sass, or a directory. If the input is a directory the --output flag must also be supplied.
Also, 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.
The --source-map option accepts a boolean value, in which case it replaces destination extension with .css.map. It also accepts path to .map file and even path to the desired directory.
When compiling a directory --source-map can either be a boolean value or a directory.
node-sass supports different configuration parameters to change settings related to the sass binary such as binary name, binary path or alternative download path. Following parameters are supported by node-sass:
| Variable name | .npmrc parameter | Process argument | Value |
|---|---|---|---|
| SASS_BINARY_NAME | sass_binary_name | --sass-binary-name | path |
| SASS_BINARY_SITE | sass_binary_site | --sass-binary-site | URL |
| SASS_BINARY_PATH | sass_binary_path | --sass-binary-path | path |
These parameters can be used as environment variable:
export SASS_BINARY_SITE=http://example.com/As local or global .npmrc configuration file:
sass_binary_site=http://example.com/As a process argument:
npm install node-sass --sass-binary-site=http://example.com/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.
Copyright (c) 2015 Andrew Nesbitt. See LICENSE for details.
v4.2.0
https://github.com/sass/node-sass/releases/tag/v4.2.0
FAQs
Wrapper around libsass
The npm package node-sass receives a total of 843,154 weekly downloads. As such, node-sass popularity was classified as popular.
We found that node-sass demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 3 open source maintainers collaborating on the project.
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