About XMLHttpRequest Object
采集日期：2008-4-24作者：lixianlin(注：本数据由系统自动采集，内容与BHCODE无关)
Retrieves the response body as an XML Document Object Model (DOM) object.Retrieves the friendly HTTP status of the request.The send method has been called, but the status and headers are not yet available.Calling the responseBody and responseText properties at this state to obtain partial results will return an error, because status and response headers are not fully available.All the data has been received, and the complete data is available in the responseBody and responseText properties.