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  • Book Overview & Buying Mastering JavaScript Promises
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Mastering JavaScript Promises

Mastering JavaScript Promises

By : Hussain
2.5 (2)
Buy this Book
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Mastering JavaScript Promises

Mastering JavaScript Promises

2.5 (2)
By: Hussain
Buy this Book

Overview of this book

This book is for all the software and web engineers wanting to apply the promises paradigm to their next project and get the best outcome from it. This book also acts as a reference for the engineers who are already using promises in their projects and want to improve their current knowledge to reach the next level. To get the most benefit from this book, you should know basic programming concepts, have a familiarity with JavaScript, and a good understanding of HTML.
Table of Contents (11 chapters)
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Preface
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Preface
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What this book covers
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What you need for this book
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Who this book is for
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Conventions
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Reader feedback
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Customer support
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1
1. Promises.js
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1. Promises.js
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The fall and rise of JavaScript
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Google's contributions to JavaScript
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Where Promises.js came in?
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What is a promise?
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Why do we need promise in JS?
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Software prerequisites
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Future, promise, and delay
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States of a promise
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How do we keep Promises.js in this book?
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Browser compatibility
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Summary
2
2. The JavaScript Asynchronous Model
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2. The JavaScript Asynchronous Model
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Programming models
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Learning the JavaScript asynchronous model
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The mechanism of a callback function in JavaScript
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The events
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The publisher/subscriber
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The promises object
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Summing up – the asynchronous programing model
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Summary
3
3. The Promise Paradigm
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3. The Promise Paradigm
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Callback, revisited
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Promise
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Deferred
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How do promise and deferred relate to each other?
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Standard behaviors of the Promise API
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Interactive promises
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The states and return values of a promise
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Common sequencing patterns
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Decoupling events and applications logic
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What promises prescribed not to do
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Promises and exceptions
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Best practices to handle exceptions in promise
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Considerations while choosing a promise
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Summary
4
4. Implementing Promises
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4. Implementing Promises
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How to implement promises
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Implementations in Java
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Say hello to JDeferred
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Mechanics of JDeferred
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Ultimate JDeferred
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Summary
5
5. Promises in WinRT
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5. Promises in WinRT
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An introduction to WinRT
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The evolution of WinRT
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A little detail about WinJS
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WinJS – its purpose and a distribution history
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HTML5, CSS3, and JavaScript
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WT with HTML5, CSS3, and JavaScript
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The need for integrating promise with WT
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Problems when using asynchronous programming
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Jumpstarting promises
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Writing a function that returns a promise
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Error handling
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Chaining promises using the then() and done() functions
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Summary
6
6. Promises in Node.js
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6. Promises in Node.js
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The V8 engine – the mechanics
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The V8 engine in Google Chrome
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The evolution of Node.js
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A brief introduction to Node.js
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Download and install Node.js
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Node Package Manager – NPM
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Choice of environment
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Setting up the environment for Node.js
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A simple node server
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Things we learned so far
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Node.js with the Q library
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Moving ahead with Q
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Propagation in Q
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Chaining and nesting promises
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Sequences in Q
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Combination in Q
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How to handle errors in Q in Node.js
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Making progress with promises
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Getting to the end of a chain of promises
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Callback-based promises versus Q-based promises
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Q.Promise() – another way to create promises
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Static methods of Q
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Promise as a proxy
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Familiarizing Node.js – the Q way
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Unbinds and its solution
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Q support for tracing stacks
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Making promise-based actions
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Object handling promises
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View revisited
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Aborting a promise
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Q utilities for Node.js
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Summary
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7. Promises in Angular.js
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7. Promises in Angular.js
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The evolution of Angular.js
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The structure of the Angular.js document
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Getting started with Angular.js
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Creating your first Angular.js file
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How to use Angular.js on your local machine
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What would be your preference for the server?
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Key elements of Angular.js
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Implementing promises in Angular.js
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The schematics of using promises in Angular.js
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Promise as a handle for callback
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Blindly passing arguments and nested promises
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Deferred objects or composed promises
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Dealing with the nested calls
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Concurrency in Angular.js
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The combination of success and error
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The safe approach
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Route your promise
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Summary
8
8. Promises in jQuery
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8. Promises in jQuery
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From where it started?
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Behind the scenes – how does jQuery work?
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Is your document ready to submit?
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How to use jQuery
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The syntax
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Caching in jQuery
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A sample example
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JavaScript before and after jQuery
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The solution – introducing promises in jQuery
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Deferred in jQuery
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$.Deferred().promise() in jQuery
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Projecting a promise in jQuery
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Joining promises with $.when
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Your own $.Deferred process
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The advent of promises in jQuery
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Summary
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9. JavaScript – The Future Is Now
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9. JavaScript – The Future Is Now
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ECMAScript 6 (ECMA 262)
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harmony:generators
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The MEAN stack
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Real-time communication in JavaScript
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Internet of Things
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Computer animation and in 3D graphics
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NoSQL databases
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Summary
10
Index
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Index

The mechanism of a callback function in JavaScript

The question here is, how on earth does a callback function work?

As we know that functions are like first class objects in JS, we can pass them around in a similar way to variables and return them as functions and use them in other functions.

When we pass a callback function as arguments to another function, we are only passing the function definition. We aren't executing functions in parameters. We are also not passing the function with the trailing pair of executing parenthesis (), as we would when we are executing a function.

Since the containing function has the callback function in its parameter as a function definition, it can execute the callback at any time.

It is important to note that the callback function is not executed immediately. It is "called back" and can still be accessed later via the arguments object by the containing function.

Basic rules to implement callbacks

There are some basic rules that you need to keep in mind while...

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Mastering JavaScript Promises
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