This is a demo of different twirl templates (html, js) used in Play.

Sbt compiles either html or js twirl templates under app/views/.

./sbt compile

And then check "target/scala-2.11/twirl/main/views/js/generic.template.scala" and you'll find "play.twirl.api.JavaScriptFormat" which is the correct interpretation since the template uses @JavaScript annotation in app/views/generic.scala.js.

Gradle only comprehends html format.

gradle wrapper --gradle-version 4.0
./gradlew compilePlayBinaryPlayTwirlTemplates

Check "build/src/play/binary/twirlTemplatesScalaSources/views/js/generic.template.scala" and you'll find "play.twirl.api.HtmlFormat" which is the incorrect format because the template specifies @JavaScript annotation. This format difference will cause rending issue in the Play front-ends.