(Judging from the documentation, this interface is still under development). The official explanation is Represents a cross-domain XML request via HTTP.
This is good news. The inability of XMLRequest to cross sites has always been a flaw of multi-subdomain servers. In many cases, the most original dynamic script and JSON methods have to be considered. However, the IE8 team intends to solve the problem of cross-site data access, which is an improvement for IE8.
But I’m worried again here. IE8 has made progress, what should I do if other browsers haven’t kept up? It would be even more cool if the ie team implemented JSONRequset. http://www.json.org/JSONRequest.html
In addition, XMLHttpRequest under ie8 adds a very important attribute timeout (Gets or sets the time-out value. ) and ontimeout (Raised when there is an error that prevents the completion of the request.) method. This is extremely important for optimization.