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ECMAScript Cookbook

You're reading from   ECMAScript Cookbook Over 70 recipes to help you learn the new ECMAScript (ES6/ES8) features and solve common JavaScript problems

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Product type Paperback
Published in Mar 2018
Publisher Packt
ISBN-13 9781788628174
Length 348 pages
Edition 1st Edition
Languages
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Author (1):
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Ross Harrison Ross Harrison
Author Profile Icon Ross Harrison
Ross Harrison
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Table of Contents (14) Chapters Close

Preface 1. Building with Modules FREE CHAPTER 2. Staying Compatible with Legacy Browsers 3. Working with Promises 4. Working with async/await and Functions 5. Web Workers, Shared Memory, and Atomics 6. Plain Objects 7. Creating Classes 8. Inheritance and Composition 9. Larger Structures with Design Patterns 10. Working with Arrays 11. Working with Maps and Symbols 12. Working with Sets 13. Other Books You May Enjoy

Creating promises with an async function


The async functions are an easy way to create and work with promises. In this recipe, we'll see a basic form of this.

Getting ready

This recipe assumes you already have a workspace that allows you to create and run ES modules in your browser. If you don't, please see the first two chapters.

How to do it...

  1. Open your command-line application and navigate to your workspace.
  2. Create a new folder named 04-01-creating-Promise-with-async.
  3. Copy or create an index.html that loads and runs a main function from main.js.
  4. Create a main.js with an async function named someTask:
// main.js 
async function someTask () { 
   console.log('Performing some task'); 
} 
  1. Create a main that calls someTask and logs messages before and after someTask is executed:
export function main () { 
  console.log('before task'); 
  someTask(); 
  console.log('after task created'); 
}  
  1. Chain a then call off of someTask and log a message in the callback function:
export function main () { 
  console...
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