Enter key prevention in multiline textfield

textfieldEnter.as

textfield.addEventListener(KeyboardEvent.KEY_UP, keyHandler);
 
private function keyHandler(event:KeyboardEvent):void {
   if(event.type == KeyboardEvent.KEY_UP && event.keyCode == Keyboard.ENTER) {
      event.target.text = event.target.text.replace("\r", "");
   }
}