1. 构造函数
2. HttpRequest
3. 属性
4. hashCode
5. on
6. onAbort
7. onError
8. onLoad
9. onLoadEnd
10. onLoadStart
11. onProgress
12. onReadyStateChange
13. onTimeout
14. readyState
15. response
16. responseHeaders
17. responseText
18. responseType
19. responseUrl
20. responseXml
21. runtimeType
22. status
23. statusText
24. timeout
25. upload
26. withCredentials
27. 方法
28. abort
29. addEventListener
30. dispatchEvent
31. getAllResponseHeaders
32. getResponseHeader
33. noSuchMethod
34. open
35. overrideMimeType
36. removeEventListener
37. send
38. setRequestHeader
39. toString
40. 运算符
41. 运算符 ==
42. 静态属性
43. supportsCrossOrigin
44. supportsLoadEndEvent
45. supportsOverrideMimeType
46. supportsProgressEvent
47. 静态方法
48. getString
49. postFormData
50. request
51. requestCrossOrigin
52. 常量
53. DONE
54. HEADERS_RECEIVED
55. LOADING
56. OPENED
57. readyStateChangeEvent
58. UNSENT