MyApp.scala

package minimal

import org.scalajs.dom
import scala.scalajs.js

object App {

  def main(args: Array[String]): Unit = {  

    // prints to console as expected
    println("hello on console")
    
    val myElement: js.Any =
      MyComponents.WelcomerCompanion.createElement(name = "Anthony")

    val myContainer: dom.raw.Element = 
      org.scalajs.dom.document.getElementById("container")
        
    Bindings.ReactDOM.render(
      element   = myElement,
      container = myContainer) 
  }

}

// ===========================================================================
object MyComponents {
  
  // @ScalaJSDefined is deprecated: add -P:scalajs:sjsDefinedByDefault to your scalac options and simply remove @ScalaJSDefined
  @js.annotation.ScalaJSDefined // removing it actually fails...
  class Welcomer(props2 /* !! calling it props causes issues !! */: js.Object) 
        extends Bindings.Component(
          props = props2) {
          
      val name: js.Dynamic = this.props.asInstanceOf[js.Dynamic].name /* uses scala.Dynamic's applyDynamic */
    
      override def render() = s"hello ${name}"
      
  }

  // ---------------------------------------------------------------------------
  object WelcomerCompanion /* !! calling it Welcomer causes issues !! */ {
    def createElement(name: String) =
      Bindings.React.createElement(
        `type`  = js.constructorOf[MyComponents.Welcomer],
         config = js.Dynamic.literal(name = name /* arbitrary "keys" thanks to scala Dynamic */) )         
  }

}