Analogy

We all know the importance of promises in our life. We even have a special day dedicated to it :) But how well do we know the importance of promises in JavaScript? Well if you don’t know it yet, it’s a great time to know it because they are becoming more and more popular. So what are promises? Let’s try to understand it through an analogy.

Suppose you are a top class rapper and you haven’t released an album for a while and fans are asking for it day and night. So what you do is that you “promise” them that whenever it will be out, all of them would be notified. To get this done you give your fans a list. They can fill in their email addresses, so that when the album becomes available, all the subscribers instantly receive it. And even if something goes wrong, say a pandemic, so that you can’t release the album, they will still be notified.

Now everyone is happy: You, because the people don’t crowd you anymore, and fans, because they won’t miss any news on the album.

This is a real-life analogy for things we often have in programming:

1. A “producing code” that does something and may take time. That’s a “rapper”.
2. A “consuming code” that wants the result of the “producing code” once it’s ready. Many functions may need that result. These are the “fans”.
3. A promise is a special JavaScript object that links the “producing code” and the “consuming code” together. In terms of our analogy: this is the “subscription list”. The “producing code” takes whatever time it needs to produce the promised result, and the “promise” makes that result available to all of the subscribed code when it’s ready.

JavaScript promises are much more complex than a simple subscription list: they have additional features and limitations. But it’s fine to begin with.

#async #promises #javascript #development #await