Minification of CSS and JS files using maven plugin not working

Question

I am trying to use the YUI compressor maven plugin in my Spring MVC Web Application by following the instructions in the http://www.baeldung.com/maven-minification-of-js-and-css-assets. I have added the following to my pom.xml file:

   <plugin>
         <groupId>net.alchim31.maven</groupId>
            <artifactId>yuicompressor-maven-plugin</artifactId>
             <version>1.5.1</version>
            <executions>
                <execution>
                    <goals>
                        <goal>compress</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <nosuffix>true</nosuffix>
               <webappDirectory>${project.build.directory}/min</webappDirectory>
                <excludes>
                    <exclude>**/*.min.js</exclude>
                    <exclude>**/handlebars-3133af2.js</exclude>
                    <exclude>**/require.js</exclude>
                </excludes>
            </configuration>
    </plugin>

I have many CSS and JS files in the sub-folders under src/main/webapp and according to the documentation, all these should be minified. But when I run the maven clean install, neither do I see any log related to minification in my console nor do I find any minified file in my war file.

All I want is to save the minified file under a subfolder named min with the same filename in the same folder as the existing CSS or JS file

The console log now is:

[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building smartwcm-services 6.3.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ smartwcm-services ---
[WARNING] Using platform encoding (Cp1252 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] Copying 36 resources
[INFO] 
[INFO] --- yuicompressor-maven-plugin:1.5.1:compress (default) @ smartwcm-services ---
[ERROR] E:\projects\smartwcm\source-code\smartwcm-services\src\main\webapp\layout\common\adminv3\ca\css\content\design\azure.js [1:2]: illegal character
[ERROR] ...E:\projects\smartwcm\source-code\smartwcm-services\src\main\webapp\layout\common\adminv3\ca\css\content\design\azure.js:line 1:column 2:illegal character
    /* Note: jquery script is assumed to be loaded prior to this script */
[ERROR] E:\projects\smartwcm\source-code\smartwcm-services\src\main\webapp\layout\common\adminv3\ca\css\content\design\azure.js [1:2]: syntax error
[ERROR] ...E:\projects\smartwcm\source-code\smartwcm-services\src\main\webapp\layout\common\adminv3\ca\css\content\design\azure.js:line 1:column 2:syntax error
    /* Note: jquery script is assumed to be loaded prior to this script */
[ERROR] E:\projects\smartwcm\source-code\smartwcm-services\src\main\webapp\layout\common\adminv3\ca\css\content\design\azure.js [1:3]: illegal character
[ERROR] ...E:\projects\smartwcm\source-code\smartwcm-services\src\main\webapp\layout\common\adminv3\ca\css\content\design\azure.js:line 1:column 3:illegal character
    /* Note: jquery script is assumed to be loaded prior to this script */
[ERROR] E:\projects\smartwcm\source-code\smartwcm-services\src\main\webapp\layout\common\adminv3\ca\css\content\design\azure.js [1:0]: Compilation produced 3 syntax errors.
[ERROR] ...E:\projects\smartwcm\source-code\smartwcm-services\src\main\webapp\layout\common\adminv3\ca\css\content\design\azure.js:line 1:column 0:Compilation produced 3 syntax errors.
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 6.060 s
[INFO] Finished at: 2016-12-29T11:25:32+05:30
[INFO] Final Memory: 19M/111M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal net.alchim31.maven:yuicompressor-maven-plugin:1.5.1:compress (default) on project smartwcm-services: Execution default of goal net.alchim31.maven:yuicompressor-maven-plugin:1.5.1:compress failed: Compilation produced 3 syntax errors. -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException

Answer 1

If you run without nosuffix option in your pom.xml like the configuration you have posted you will get mimimised files in target\min folder. You will see below log in maven

[INFO] --- yuicompressor-maven-plugin:1.5.1:compress (default) @ spring-static-resources ---
[INFO] bootstrap.css (127343b) -> bootstrap-min.css (106005b)[83%]
[INFO] foo.js (44b) -> foo-min.js (37b)[84%]
[INFO] utils.js (48b) -> utils-min.js (28b)[58%]
[INFO] main.js (138b) -> main-min.js (100b)[72%]
[INFO] router.js (86b) -> router-min.js (64b)[74%]
[INFO] bootstrap.css (127343b) -> bootstrap-min.css (106005b)[83%]
[INFO] foo.js (44b) -> foo-min.js (37b)[84%]
[INFO] bootstrap.css (127343b) -> bootstrap-min.css (106005b)[83%]
[INFO] myCss.css (127343b) -> myCss-min.css (106005b)[83%]
[INFO] bootstrap.css (127343b) -> bootstrap-min.css (106005b)[83%]
[INFO] total input (637075b) -> output (530291b)[83%]

When you run with <nosuffix>true</nosuffix> you will get below log. This option will give you minified files in target\min folder but will keep the file name same.

[INFO] --- yuicompressor-maven-plugin:1.5.1:compress (default) @ spring-static-resources ---
[INFO] bootstrap.css (127343b) -> bootstrap.css (106005b)[83%]
[INFO] foo.js (44b) -> foo.js (37b)[84%]
[INFO] utils.js (48b) -> utils.js (28b)[58%]
[INFO] main.js (138b) -> main.js (100b)[72%]
[INFO] router.js (86b) -> router.js (64b)[74%]
[INFO] bootstrap.css (127343b) -> bootstrap.css (106005b)[83%]
[INFO] foo.js (44b) -> foo.js (37b)[84%]
[INFO] bootstrap.css (127343b) -> bootstrap.css (106005b)[83%]
[INFO] myCss.css (127343b) -> myCss.css (106005b)[83%]
[INFO] bootstrap.css (127343b) -> bootstrap.css (106005b)[83%]
[INFO] total input (637075b) -> output (530291b)[83%]

To include these minimised files in war and not the original ones you need to set <webappDirectory> in pom.xml. So your configuration should look like below

 <plugin>
         <groupId>net.alchim31.maven</groupId>
            <artifactId>yuicompressor-maven-plugin</artifactId>
            <version>${yuicompressor-maven-plugin.version}</version>
            <executions>
                <execution>
                    <goals>
                        <goal>compress</goal>
                    </goals>
                </execution>
            </executions>
            <configuration>
                <nosuffix>true</nosuffix>
               <webappDirectory>${project.build.directory}/min</webappDirectory>
                <excludes>
                    <exclude>**/*.min.js</exclude>
                    <exclude>**/handlebars-3133af2.js</exclude>
                    <exclude>**/require.js</exclude>
                </excludes>
            </configuration>
    </plugin>

Above logs are from github project https://github.com/eugenp/tutorials/tree/master/handling-spring-static-resources. Check the pom.xml for reference in this project.