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In this lecture, we are going to quickly recap the flattening operators.

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The overall goal of a flattening operator is to subscribe to inner observables.

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Their values will get pushed onto the next operator.

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They are much easier to use than chaining subscriber functions.

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We have various options at our disposal for creating a flattening operator.

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I'll give an analogy for each operator.

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Let's say you're a chef at a restaurant.

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As orders come in, you need to decide how to prioritize each order.

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There are various systems you can use for determining how to treat new orders.

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What would you do if an order comes in as you're working on another order?

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If you were to use the Switch Map operator, you would stop working on whatever order you were on.

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The latest order takes priority.

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Probably not the best idea to ditch an order.

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Let's look at a different option.

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The cat map operator dictates all orders are important, but only one order should be worked on at a

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time.

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The other orders are queued until the first order is complete.

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Orders are worked on in the order they are given.

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The Merge Map operator will accept all orders.

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Orders can be worked on in parallel.

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New orders do not impact existing active orders.

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Lastly, the exhaust map operator will ignore new orders until the active order is finished.

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Once the active order is completed, a new order can be given.

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As you can see, flattening operators come in all shapes and sizes.

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Learning how to use flattening operators is very important.

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It's likely you will run into a scenario where you'll need to manage inner subscriptions.

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Choosing the right operator will give you the desired behavior and effect you're looking for in your

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app.

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We're finished learning about our SJS.

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We spent a lot of time learning about observables and operators at this point.

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You should be more than comfortable with working with our SJS code in an app.

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Angular and other libraries use our SJS behind the scenes in the next couple of sections.

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We will encounter observables.

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Handling observables and angular is not much different than handling them with vanilla JavaScript.

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So when you're ready, I'll see you there.