We’ve already had a glimpse at Server-Sent Events (also known as EventSource, and I’ll switch between the two to keep you on your toes) in my Methods of Communication article from last year. In this article, I want to delve in to more detail about the SSE API, demonstrate its features, and even show you how to polyfill browsers that lack EventSource support.

By now, you've surely realised that 'HTML5' is so much more than just markup. There's also an army of associated JavaScript APIs. Among the ranks are a few new technologies that open up how we communicate between client and server and across documents. Let's take a look.