Minify .js files during Maven builds

Minifying files for use on the web is essential to improving performance, to reduce network overhead as well as a slight bump in execution speed.

Long ago I used the YUICompressor plugin for both JS as well as CSS files, unfortunately that project appears to have been abandoned many years ago and no longer functions well for JS files that make use of modern features.

For JS files, I’ve found that most capabilities can be replicated with the following in the pom.xml:

<plugin>
<groupId>com.github.blutorange</groupId>
<artifactId>closure-compiler-maven-plugin</artifactId>
<version>2.21.0</version>
<executions>
<execution>
<id>default-minify-js</id>
<phase>generate-resources</phase>
<configuration>
<!-- not supported (always uses .min) <suffix>-min</suffix> -->
<encoding>UTF-8</encoding>
<baseSourceDir>${basedir}/${webapp-folder}</baseSourceDir>
<baseTargetDir>${webapp.path}/</baseTargetDir>
<sourceDir>js</sourceDir>
<targetDir>js</targetDir>
<skipMerge>true</skipMerge>
<includes>
<include>**/*.js</include>
</includes>
<excludes>
<exclude>**/webjars-requirejs.js</exclude>
<exclude>**/bootstrap*.*</exclude>
<exclude>**/jasmine*.*</exclude>
<exclude>**/*-min.js</exclude>
<exclude>**/*.min.js</exclude>
</excludes>
</configuration>
<goals>
<goal>minify</goal>
</goals>
</execution>
</executions>
</plugin>

NOTE: the only feature I have not yet been able to match is the suffix, as it appears to always use *.min.js (where I used to prefer *-min.js).

An additional advantage of using the plugin is that many common syntax errors will be identified at build time, before they cause user problems… but they will also break your build!

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