Understanding JavaScript Promises
Understanding JavaScript Promises
About the Book
Since promises were added to JavaScript in 2015, they have become an integral part of the language. A good understanding of how promises work is more important than ever in becoming a proficient JavaScript developer. This book is written to introduce the promises and their intricacies in a straightforward, easy to read format. Each chapter is filled with practical, real-world examples using the techniques discussed, and all examples are available for download with your purchase.
What you'll learn:
- Which parts of promises are synchronous and which are asynchronous
- How to effectively use promise chains to simplify your code
- The best way to catch errors in promises
- How to create your own promises
- Ways to work with multiple promises at once
- How async functions and await expression hide promise complexities
- How to abort asynchronous functions and create your own abortable functions
- What happens to rejected promises without rejection handlers
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Translations
About the Author
Table of Contents
-
Introduction
- About This Book
- Acknowledgments
- About the Author
- Disclaimer
-
1. Promise Basics
- The Promise Lifecycle
- Creating New (Unsettled) Promises
- Creating Settled Promises
- Summary
-
2. Chaining Promises
- Catching Errors
- Using finally() in Promise Chains
- Returning Values in Promise Chains
- Returning Promises in Promise Chains
- Summary
-
3. Working with Multiple Promises
- The Promise.all() Method
- The Promise.allSettled() Method
- The Promise.any() Method
- The Promise.race() Method
- Summary
-
4. Async Functions and Await Expressions
- Defining Async Functions
- What Makes Async Functions Different
- Summary
-
5. Abortable Functions
-
Using an
AbortControllerObject -
Custom Signals with
AbortSignal - Creating Abortable Functions
- Summary
-
Using an
-
6. Unhandled Rejection Tracking
- Detecting Unhandled Rejections
- Web Browser Unhandled Rejection Tracking
- Node.js Unhandled Rejection Tracking
- Summary
-
Final Thoughts
- Download the Extras
- Help and Support
- Follow the Author
- Notes
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