Announcing Scala.js 1.13.2

Jun 23, 2023.

We are pleased to announce the release of Scala.js 1.13.2!

This release mostly contains bug fixes. It also upgrades the Scala standard library to versions 2.12.18 and 2.13.11.

Due to a deep incompatibility between sbt 1.6+ and Scala 2.12.4, we have dropped support for that particular version of Scala. Other Scala 2.12.2+ versions are still supported.

This release is the first to be built with sbt 1.9.x, which means that our sbt plugin sbt-scalajs is now dual-published on Maven Central using the legacy Ivy style and the new Maven-compliant style. The transitive dependency sbt-platform-deps is also dual-published. See the release notes of sbt 1.9.0 for more information.

Read on for more details.

Getting started

If you are new to Scala.js, head over to the tutorial.

If you need help with anything related to Scala.js, you may find our community in #scala-js on Discord and on Stack Overflow.

Bug reports can be filed on GitHub.

Release notes

If upgrading from Scala.js 0.6.x, make sure to read the release notes of Scala.js 1.0.0 first, as they contain a host of important information, including breaking changes.

This is a patch release:

  • It is backward binary compatible with all earlier versions in the 1.x series: libraries compiled with 1.0.x through 1.13.1 can be used with 1.13.2 without change.
  • It is forward binary compatible with 1.13.0 and 1.13.1: libraries compiled with 1.13.2 can be used with previous 1.13.x versions without change.
  • It is backward source compatible with 1.13.0 and 1.13.1: source code that used to compile with previous 1.13.x versions should compile as is when upgrading to 1.13.2.

In addition, like Scala.js 1.13.0:

  • It is not forward binary compatible with 1.12.x: libraries compiled with 1.13.2 cannot be used with 1.12.x or earlier.
  • It is not entirely backward source compatible with 1.12.x: it is not guaranteed that a codebase will compile as is when upgrading from 1.12.x or earlier (in particular in the presence of -Xfatal-warnings).

As a reminder, libraries compiled with 0.6.x cannot be used with Scala.js 1.x; they must be republished with 1.x first.



This release adds support for the following JDK classes:

  • java.util.StringJoiner

Bug fixes

Among others, the following bugs have been fixed in 1.13.2:

  • #4850 ClassDef checker error after linking when only using the class data of a non-native JS class
  • #4855 Linker emits modules with colliding names on case-insensitive filesystems
  • #4865 IllegalArgumentException: A constructor or static initializer must have a void result type
  • #4870 UndefinedBehaviorError: java.lang.NegativeArraySizeException in BigInteger
  • #4878 StringIndexOutOfBoundsException in String.regionMatches
  • dotty#17542 Scala.js IR error expected but java.lang.Class found

You can find the full list on GitHub.