Simply add the following line to your project/plugins.sbt (note that this line must be placed before addSbtPlugin("org.scala-js" % "sbt-scalajs" % <scalajs-version>); otherwise you may get errors such as java.lang.NoSuchMethodError: when you run tests):

// For Scala.js 0.6.x
libraryDependencies += "org.scala-js" %% "scalajs-env-selenium" % "0.3.0"

// For Scala.js 1.x
libraryDependencies += "org.scala-js" %% "scalajs-env-selenium" % "1.1.1"

and the following line to your sbt settings:

// Apply to the 'run' command
jsEnv := new org.scalajs.jsenv.selenium.SeleniumJSEnv(capabilities)

// Apply to tests
jsEnv in Test := new org.scalajs.jsenv.selenium.SeleniumJSEnv(capabilities)

where capabilities is one of the members of org.openqa.selenium.remote.DesiredCapabilities.

For example for Firefox:

jsEnv := new org.scalajs.jsenv.selenium.SeleniumJSEnv(
    new org.openqa.selenium.firefox.FirefoxOptions())

You are responsible for installing the drivers needed for the browsers you request.

When executing the program with run a new browser window will be created, the code will be executed in it and finally the browser will close itself. All the console outputs will appear in SBT as usual. Executing test will open several browser windows and close them all before the end of the tests.

In browser debugging

If you wish to keep the browser window opened after the execution has terminated simply add the option withKeepAlive on the environment:

new SeleniumJSEnv(capabilities, SeleniumJSEnv.Config().withKeepAlive(true))

It is recommend to use this with a run and not test because the latter tends to leave too many browser windows open.

Debugging tests on a single window

By default tests are executed in their own window for parallelism. When debugging tests with withKeepAlive it is possible to disable this option using the sbt setting parallelExecution in Test := false.

Headless Usage

It is often desirable to run Selenium headlessly. This could be to run tests on a server without graphics, or to just prevent browser windows popping up when running locally.


A common approach on Linux and Mac OSX, is to use xvfb, "X Virtual FrameBuffer". It starts an X server headlessly, without the need for a graphics driver.

Once you have xvfb installed, usage here with SBT is as simple as:

Xvfb :1 &
DISPLAY=:1 sbt

The :1 indicates the X display-number, which is a means to uniquely identify an X server on a host. The 1 is completely arbitrary—you can choose any number so long as there isn't another X server running that's already associated with it.


scalajs-env-selenium is distributed under the BSD 3-Clause license.


Follow the contributing guide.