An sbt-web plugin to perform terser optimization on the asset pipeline.
uglify-es is no longer maintained and uglify-js does not support ES6+.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.
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.
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.
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.