addEventListener method Null safety

void addEventListener (
  1. String type,
  2. EventListener? listener,
  3. [bool? useCapture]
)
override

Implementation

void addEventListener(String type, EventListener? listener,
    [bool? useCapture]) {
  // Messages posted to ports are initially paused, allowing listeners to be
  // setup, start() needs to be explicitly invoked to begin handling messages.
  if (type == 'message') {
    _start();
  }

  super.addEventListener(type, listener, useCapture);
}