object MainApp {
  def main(args: Array[String]): Unit = {
    println(new B())
  }
}

class B extends A

@js.native
@JSImport("example", "A")
class A extends js.Object

TypeError: Class constructor A cannot be invoked without 'new'

/** @constructor */
var $c_LB = (function $c_LB() {
    $i_$0040test$002dtest$002ftest.B.call(this)
});