FREE e-book

Understanding JavaScript Promises

Learn all about asynchronous programming with promises in JavaScript. New and updated for 2022!

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    “I've worked to make this e-book easy to follow to teach promises in a straightforward way. I hope you enjoy it!”

    Nicholas C. Zakas


    What you'll learn:

    1. What a promise is
    2. What then(), catch() and finally() actually do
    3. Which parts of promises are actually asynchronous
    4. How to operate on multiple promises at once
    5. How to chain multiple promises together


    You can purchase the full version of this ebook on Leanpub or Amazon. The full ebook contains two additional chapters covering:

    • Async functions and await expressions
    • Unhandled rejection tracking

    These extra chapters are only available in the full version of the book.

    What is it all about?

    Since they were introduced in 2015, promises have become an important part of the JavaScript language. All new asynchronous APIs are built on promises, and as such, it's important for developers to have a good understanding of how promises work.

    In this book, you'll learn all of the ins and outs of promises, from basics such as how to create promises all the way to understanding how async functions work with promises behind-the-scenes.

    Veteran JavaScript book author Nicholas C. Zakas has been writing about JavaScript for over 15 years and this ebook brings his years of industry experience to the foreground to provide real-world examples and insights.