Rx foundations

Although it may sound repetitive, it is so important to understand the foundations of Rx and the key design patterns that govern Rx. Being a book on patterns and idioms, it would be really gratifying to know if any interested reader would benefit from understanding the underpinnings of these keys concepts as they are realized in the host language (JS in this case) directly or via libraries.

The two key design patterns based on which Rx works are the observer and iterator patterns. Let's have a quick look at how these patterns are implemented, and then speculate or peek at a possible implementation of RxJS. This way of learning would really help in forming a deeper understanding of the core concepts. And not to hide the fact that the authors themselves have attempted to create a JS library (code-named YieldJS on GitHub at http://shinexavier.github.io/YieldJS/), which gives the rudimentary capability of RxJS despite being a pull-based implementation. However, one thing...