[Traubenfuchs]

There is also an online tool / API for this, which can be quite helpful for non npm using vanilla.js workflows.

https://closure-compiler.appspot.com/

Should be set to:

  // @language_in UNSTABLE
  // @language_out ECMASCRIPT_NEXT

for it to work as expected.

[palsecam]

You’re right, however for offline but non npm workflow, you can also use the Closure Compiler JAR, grabbed for instance from Maven: https://mvnrepository.com/artifact/com.google.javascript/clo...

   $ wget https://repo1.maven.org/maven2/com/google/javascript/closure-compiler/v20230502/closure-compiler-v20230502.jar
   […]
   $ java -jar closure-compiler-v20230502.jar 
   The compiler is waiting for input via stdin.

The Closure Compiler still is a Java project. It just gets primarily distributed via NPM these days.