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This is an UglifyJS plugin for Metalsmith and is a successor to the original plugin written by Keith Smith.


Install the package:

npm install metalsmith-uglify

Add the plugin to your Metalsmith build chain:

var metalsmith = require('metalsmith');
var uglify = require('metalsmith-uglify');

    .build(function (err) {
        if (err) {
            throw err;

        console.log('Build complete');


The plugin function accepts a configuration object as the first argument.

  • {boolean} - Set to use uglify-es package instead of uglify-js. It will set also set options.uglify.ecma = 6 by default.

  • {object} options.concat - Set to concatenate to a single bundle file. UglifyJS does not provide any ordering guarantees.

    • {string} options.concat.file - Name of the bundle file. Default is scripts.min.js.

    • {string} options.concat.root - Set to limit the plugin to a specific source directory. This option overrides options.root.

  • {function} options.filter - Function to filter the list of JavaScript files. By default .min.js files are excluded.

  • {string} options.root - Set to limit the plugin to a specific source directory.

  • {boolean} options.removeOriginal - Set to keep the original (unminified) file from being included in the output directory.

  • {boolean} options.sameName - Set to keep minified name as is without adding .min. This option overrides options.removeOriginal and is ignored if options.concat is set.

  • {object} options.uglify - UglifyJS configuration (see UglifyJS docs). Default is { sourceMap: { includeSources: true } }.

Upgrading from version 1.x

Version 2 is a rewrite of the plugin with significant breaking changes to the options object.

Please refer to the upgrade document for more information.


To build the example page run:

make example

Inspect files in example/ for more information.

Debug Logging

Set the DEBUG variable to see what the plugin is doing.

If you are troubleshooting the plugin itself then the following should be enough:

DEBUG=metalsmith-uglify:info:* node build.js

If you think the problem is actually related to something UglifyJS does then you can get more detail:

DEBUG=metalsmith-uglify:* node build.js