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