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A fork (of a fork of a fork) of the seemingly abandoned sbt-uglify plugin.


To use this plugin, use the addSbtPlugin command within your project's plugins.sbt file:

addSbtPlugin("org.danielnixon" % "sbt-uglify" % "1.0.7")

Your project's build file also needs to enable sbt-web plugins. For example, with build.sbt:

lazy val root = (project in file(".")).enablePlugins(SbtWeb)

As with all sbt-web asset pipeline plugins you must declare their order of execution:

pipelineStages := Seq(uglify)

A standard build profile for the Uglify optimizer is provided which will mangle variables for obfuscation and compression. Each input .js file found in your assets folders will have a corresponding .min.js file and source maps will also be generated.


If you wish to limit or extend what is uglified then you can use filters:

includeFilter in uglify := GlobFilter("myjs/*.js"),

...where the above will include only those files under the myjs folder.

The sbt excludeFilter is also available to the uglify scope and defaults to excluding the public folder and extracted Webjars.


If you wish to change how files are mapped from input to output, you can change the uglifyOps setting to point at another grouping.

The default ops takes a source file and produces minified file and source map:

UglifyKeys.uglifyOps := UglifyOps.singleFileWithSourceMapOut

This ops takes a source file and produces minified file only (no source map):

UglifyKeys.uglifyOps := UglifyOps.singleFile

This ops takes a source file and source map and produces minified file and combined source map. Your includeFilter must include source map files for this to work:

UglifyKeys.uglifyOps := UglifyOps.singleFileWithSourceMapInAndOut


You are able to use and/or customize settings already made, and add your own. Here are a list of relevant settings and their meanings (please refer to the UglifyJS documentation for details on the options):

Option Description Default
comments Specifies comments handling. None
compress Enables compression. Set true to compress. true
compressOptions A sequence of options for compression such as hoist_vars, if_return etc. Nil
define Define globals. None
enclose Enclose in one big function. false
includeSource Include the content of source files in the source map as the sourcesContent property. false
mangle Enables name mangling. true
mangleOptions Options for mangling such as sort, topLevel etc. Nil
preamble Any preamble to include at the start of the output. None
reserved Reserved names to exclude from mangling. Nil
uglifyOps A function defining how to combine input files into output files. UglifyOps.singleFileWithSourceMapOut

The plugin is built on top of JavaScript Engine which supports different JavaScript runtimes.

© Typesafe Inc., 2014