scalajs-logging is a tiny logging API for use by the Scala.js linker and JS environments. It is not a general-purpose logging library, and you should probably not use it other than to interface with the Scala.js linker API and the JSEnv API.

Normally you should receive the dependency on scalajs-logging through scalajs-linker or scalajs-js-envs. If you really want to use it somewhere else, add the following line to your settings:

libraryDependencies += "org.scala-js" %% "scalajs-logging" % "1.1.1"

import org.scalajs.logging._

// get a logger that discards all logs
val logger = NullLogger // discard all logs

// or get a logger that prints all logs of severity Warn and above to the console
val logger = new ScalaConsoleLogger(Level.Error)

// or create your own Logger:
val logger = new Logger {
  def log(level: Level, message: => String): Unit = ???
  def trace(t: => Throwable): Unit = ???
}

then give your logger instance to an API.

Available severity levels are Debug, Info, Warn and Error.

For more details, consult the Scaladoc of scalajs-logging.