ReactClassExample.scala

@ScalaJSDefined
class Hello extends React.Component {
   def render() = {
    Reac.createElement("div")
  }
}

// render
React.render(React.createFactory(new Hello()), dom.document.body)

//error

Uncaught Error: Invariant Violation: React.render(): Invalid component element. Instead of passing a component class, make sure to instantiate it by passing it to React.createElement.