How to implement SaxContentHandler from Javascript?

Is there a relatively feasable cross-browser way of implementing nsISaxContentHandler/ISaxContentHandler in javascript?

I'm asking because I've always been surprised to see most XmlHttpRequest platforms wait until the response to get fully transmitted. Though it's advisable to keep data fetched over XmlHttpReq开发者_Go百科uests as small as possible, it would be interesting to show each item of a list as soon as it gets in.