Understanding the Core Ideas of Promise by Implementing it in JavaScript
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Understanding the Core Ideas of Promise by Implementing it in JavaScript

Implement promise from scratch (in an evolutionary way) to grasp its core ideas

About the Book

In this book you will understand the main ideas of the promise pattern in JavaScript in an evolutionary way, which means at first you would start with nothing and try to meet the needs and improve them slowly. You would touch everything with your mind. After reading this book you will be able to implement a promise framework from scratch. Because of learning the basic concepts in this pattern you might even can see other capabilities there and decide to design a new pattern or evolve a special idea in this pattern.

About the Author

Babak Gholamzadeh
Babak Gholamzadeh

I'm a Node.js guy, who programs to solve problems. My main passion is understanding the core concepts and seeing the background of ideas.

Table of Contents

  • Introduction
  • Start the journey from the simple callback pattern to promise
  • Start with a simple variable
    • A brief explanation about primitive and non-primitive types in JavaScript
  • Initialize with an object instead of undefined
  • Define done method on the object
  • Send the callback to the object
  • Define resolve method
  • Refactor the code
  • Handle the errors
  • Modularize the code
  • Register callbacks after resolving
  • Eliminate nesting by chainable object
    • Create a chainable object
    • Create a thenable object
  • Eliminate nesting of thenable object
  • Register several callbacks before resolving
  • Implement catch method
  • Implement resolve and reject as static functions
  • Conclusion

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