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sbt-terser

Download Build Status Apache License V.2

An sbt-web plugin to perform terser optimization on the asset pipeline.

Why choose terser?

uglify-es is no longer maintained and uglify-js does not support ES6+.

terser is a fork of uglify-es that mostly retains API and CLI compatibility with uglify-es and uglify-js@3.

Usage

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

addSbtPlugin("com.github.andriimartynov" % "sbt-terser" % "0.0.1")

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(terser)

A standard build profile for the terser 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.

includeFilter

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

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

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

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

Settings

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 terser documentation for details on the options):

Option Description Default
terserBeautifyOptions Specify output options. None
terserComments Preserve copyright comments in the output. None
terserCompress Enable compressor. false
terserCompressOptions Enable compressor/specify compressor options. None
terserConfigFile Read minify() options from JSON file. None
terserDefinitionsOptions Global definitions. None
terserEcma Specify ECMAScript release. None
terserIE8 Support non-standard Internet Explorer 8. false
terserKeepClassNames Do not mangle/drop class names. false
terserKeepFNames Do not mangle/drop function names. false
terserMangle Mangle names. false
terserMangleOptions Mangle names/specify mangler options. None
terserMangleProps Mangle properties/specify mangler options. None
terserModule Input is an ES6 module. false
terserNameCacheFile File to hold mangled name mappings. None
terserSafari10 Support non-standard Safari 10/11. false
terserTimings Display operations run time on STDERR. false
terserToplevel Compress and/or mangle variables in top level scope. false
terserVerbose Print diagnostic messages. false
terserWarn Print warning messages. true
terserWrap Embed everything in a big function, making the “exports” and “global” variables available. None

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