You need to access the JavaScript global scope from Scala.js, in order to call functions like alert, prompt, console, etc.


What we need is the global value, which is a “view” of the JavaScript global scope.

It can be imported like this:


Alternatively, you can import it like this:

import scala.scalajs.js
import js.Dynamic.{ global => g }

The latter might be more convenient way, since it imports the whole js package and renames global to something more easy to use (just g).

Now let’s issue an alert from Scala. Import the global scope and add this to your main class:

def main(): Unit = {
  g.alert("Hello from Scala")

After re-compiling and re-loading the host page, you should see the corresponding browser alert.

Let’s write something to the JavaScript console. Change your main class to look like this:

def main(): Unit = {
  g.console.log("Logged a message from Scala")

Re-compile and re-load. If you open your JavaScript console, you should see the message.