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Express middleware that compiles sass to css using the locally installed node-sass


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Express middleware that will compile any .scss or .sass files in the response stream and deliver the resulting CSS. If syntax errors are encountered an error will be displayed very prominently in the browser, giving useful feedback on where to fix the problem.

This module requires node-sass to run, but it will only look for it when it actually encounters a file that needs to be compiled for the first time. This leaves the installation of the node-sass dependency up to the individual user and lets tool makers use this middleware without introducing unneeded dependencies into projects that aren't using sass. An error message will inform the user of any missing node-sass installation.

Unless disabled, express-compile-sass will set up file watchers on every .scss file that has been compiled in the life time of the server, and update the atime and mtime of the main file that included the updated file. This lets you hook in file watching middlewares to notify the browser of any updates to the CSS.

The module will attempt to leverage both browser and server in-memory cache in order to reduce the sass compiling workload, thus giving you very fast responses on subsequent loads.

Middleware Usage

var express = require('express'),
    app = express(),
    compileSass = require('express-compile-sass'),
    root = process.cwd();
    root: root,
    sourceMap: true, // Includes Base64 encoded source maps in output css 
    sourceComments: true, // Includes source comments in output css 
    watchFiles: true, // Watches sass files and updates mtime on main files for each change 
    logToConsole: false // If true, will log to console.error on errors 
console.log('Listening on port: 5000');

Browser Usage

<link rel="stylesheet" type="text/css" href="style/main.scss">



  • Switched from importing node-sass directly. Now uses node-sass-evergreen to have more features and better backwards compatibility with older node versions
  • options.sourceMap now correctly includes source maps instead of soruce comments
  • options.sourceComments now adds source comments to output


  • Removed the strict typing and stopped looking at Accept-headers. Now matches files with extensions .scss and .sass.
  • No longer pass the request down the chain with express-hijackresponse. The only reason for it was possible non-filesystem proxy mappings, which would not work with the sass compilers @import statements anyway.
  • Cache etag and response body to reduce sass compiling workload. File watch callbacks act as cache busters.