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 but is still effective for CSS even if it is less useful for modern JS.
NOTE: default extension uses -min, to change it set property ‘maven.yuicompressor.suffix’ to the desired value, such as .min to match GCC used for JS.
For CSS files, you can use following in the pom.xml (JS is also possible if you are not using ES6 features):
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>yuicompressor-maven-plugin</artifactId>
<version>1.5.1</version>
<executions>
<execution>
<id>compressyui-min</id>
<phase>prepare-package</phase>
<goals>
<goal>jslint</goal>
<goal>compress</goal>
</goals>
</execution>
</executions>
<configuration>
<nosuffix>false</nosuffix><!-- false will create -min versions, true does not -->
<warSourceDirectory>${basedir}/${webapp-folder}</warSourceDirectory>
<webappDirectory>${webapp.path}/</webappDirectory>
<jswarn>false</jswarn>
<gzip>false</gzip><!-- create .min.gz files -->
<nocompress>false</nocompress>
<force>true</force>
<excludes>
<exclude>**/*.js</exclude><!-- YUI cannot handle ES6 const let, use closure-compiler instead -->
<exclude>${webjars-output.path}*.*</exclude>
<exclude>**/webjars-requirejs.js</exclude>
<exclude>**/bootstrap*.*</exclude>
<exclude>**/jasmine*.*</exclude>
<exclude>**/*-min.css</exclude>
<exclude>**/*.min.css</exclude>
</excludes>
</configuration>
</plugin>
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