How to open Javadoc JAR file in web browser
- Rename the file scalajs-stubs_2.13.0-RC2-1.0.0-RC1-javadoc.jar to scalajs-stubs_2.13.0-RC2-1.0.0-RC1-javadoc.zip
- Use your favourite unzip tool (WinRAR / WinZIP) to extract it, now you have a folder scalajs-stubs_2.13.0-RC2-1.0.0-RC1-javadoc
- Double click index.html will open the index page on your default web browser.
How to generate Javadoc from a source JAR?
Running the command javadoc:
javadoc --ignore-source-errors -encoding UTF-8 -sourcepath "scalajs-stubs_2.13.0-RC2-1.0.0-RC1-sources.jar" -d "scalajs-stubs_2.13.0-RC2-1.0.0-RC1-javadoc" -subpackages 
