1. 构造函数
  2. ExtendableEvent
  3. 属性
  4. bubbles
  5. cancelable
  6. composed
  7. currentTarget
  8. defaultPrevented
  9. eventPhase
  10. hashCode
  11. isTrusted
  12. matchingTarget
  13. path
  14. runtimeType
  15. target
  16. timeStamp
  17. type
  18. 方法
  19. composedPath
  20. noSuchMethod
  21. preventDefault
  22. stopImmediatePropagation
  23. stopPropagation
  24. toString
  25. waitUntil
  26. 运算符
  27. 运算符 ==