SSE is plain HTTP, and might be illustrative to look[1] at the HTTP response directly so that you can convince yourself of this. EventSource is simply an imple

SSE is plain HTTP, and might be illustrative to look[1] at the HTTP response directly so that you can convince yourself of this. EventSource is simply an implementation of a parser of those messages. The problem is that MSIE and Chrome often delay dispatching content-received (XMLHttpRequest readyState=3) handlers until a certain number of bytes have been received (or in certain other circumstances, such as in Chrome's native implementation of EventSource). The bytes-received is solved by simply starting with some padding, and unless you need framing you might find it simpler to just use XMLHttpRequest directly. [1]: http://www.html5rocks.com/en/tutorials/eventsource/basics/ http://www.html5rocks.com/en/tutorials/eventsource/basics/