非标
此特征是非标准的，且不在标准轨道中。不要在面向 Web 的生产站点中使用它：它不适用于每个用户。实现之间可能存在大的不兼容性，且行为将来可能改变。
从 Gecko 22 起已过时
This Gecko-only feature was removed in Firefox/Gecko 22.
请使用
Server-Sent Events
,
Web Sockets
，或
responseText
from progress events instead.
This boolean indicates if the response is expected to be a stream of possibly multiple XML documents.
若设为
true
, the content type of the initial response must be
multipart/x-mixed-replace
or an error will occur. All requests must be asynchronous.
This enables support for server push; for each XML document that's written to this request, a new XML DOM document is created and the
onload
handler is called between documents.
注意：
When this is set, the
onload
handler and other event handlers are not reset after the first XMLdocument is loaded, and the
onload
handler is called after each part of the response is received.
XMLHttpRequest