Let's start with a recap of the previous chapter and remind ourselves how far we have come already in understanding RxJS. We learned about concepts such as  Observable, Observer, and Producer, and how they interplay. Furthermore, we got insight into the subscription process so we could actually receive our coveted values. We also looked at how unsubscribing from streams works and in which cases it is necessary to define such a behavior. Lastly, we got our hands dirty by learning how to build a core implementation of RxJS and thereby got to see all those concepts in action. Armed with all that knowledge, we should feel quite confident about the foundation of RxJS, but as was mentioned in the last chapter, we need help from operators to actually do something meaningful with our streams. 

Let's not delay any further and start talking about this chapter. Operators are functions we can call on our streams to perform manipulation in many different ways. Operators are immutable, which makes the stream easy to reason about and will also make it quite easy to test. As you will see throughout this chapter, we will seldom deal with just one stream, but many streams, and it is understanding how to forge and control these streams that allows you to go from thinking it's dark magic to actually being able to apply RxJS when and where you need it.

In this chapter, we will cover:

• How to use basic operators
• Debugging streams with operators as well as with existing tools
• Digging deeper into different operator categories
• Developing the mindset to solve a problem the Rx way