> Observables are all the hype in javascript ? Well, great, I've learnt that pattern 15 years ago... Well, the listener/observer pattern is used to explain obs

> Observables are all the hype in javascript ? Well, great, I've learnt that pattern 15 years ago... Well, the listener/observer pattern is used to explain observables in order to make them familiar, but no, it's not the same thing. Observables are streams and you work with them the via composition of streams. When viewed from that high level, the underlying protocol (the observer) becomes irrelevant and in fact, if you're often finding yourself working with that protocol, you're doing it wrong. People familiar with functional programming will be very familiar with this style, because composition is very natural to an FP developer and the composition of all kinds of streams is in the repertoire of FP developers. But I've seen plenty of colleagues, who are otherwise very capable people, really struggle with the concepts involved. The mentality shift from the imperative programming that people have been taught, to describing actions via function composition and then doing evaluation "at the end of the world" is a mind fuck. Interestingly, functional programming has been with us for some time, being older than Java. However people are not interested in actual functional programming and more recently there's this trend to classify junk as FP, just because you've got a shitty API that takes functions (often doing side effects) as arguments to other functions, but that's not FP. So going back to Observables, as a piece of advice, don't mention that in an interview ;-)