- https://surveys.jetbrains.com/s3/kotlin-slack-sign-up - join the Kotlin slack and come to the #javascript channel for questions about language features
- https://kotlinlang.org/docs/js-project-setup.html - official Jetbrains documentation
- https://kotlinlang.org/api/latest/jvm/stdlib/ - Kotlin class docs (scroll down to the org.w3c.* sections, of which there are many)