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Mastering JavaScript Promises

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Mastering JavaScript Promises

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Mastering JavaScript Promises
Jul, 2015 | 188 pages
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Table of Contents (16 chapters)
Mastering JavaScript Promises
Mastering JavaScript Promises
Credits
Credits
About the Author
About the Author
About the Reviewers
About the Reviewers
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Promises.js
Promises.js
The fall and rise of JavaScript
Google's contributions to JavaScript
Where Promises.js came in?
What is a promise?
Why do we need promise in JS?
Software prerequisites
Future, promise, and delay
States of a promise
How do we keep Promises.js in this book?
Browser compatibility
Summary
2
The JavaScript Asynchronous Model
The JavaScript Asynchronous Model
Programming models
Learning the JavaScript asynchronous model
The mechanism of a callback function in JavaScript
The events
The publisher/subscriber
The promises object
Summing up – the asynchronous programing model
Summary
3
The Promise Paradigm
The Promise Paradigm
Callback, revisited
Promise
Deferred
How do promise and deferred relate to each other?
Standard behaviors of the Promise API
Interactive promises
The states and return values of a promise
Common sequencing patterns
Decoupling events and applications logic
What promises prescribed not to do
Promises and exceptions
Best practices to handle exceptions in promise
Considerations while choosing a promise
Summary
4
Implementing Promises
Implementing Promises
How to implement promises
Implementations in Java
Say hello to JDeferred
Mechanics of JDeferred
Ultimate JDeferred
Summary
5
Promises in WinRT
Promises in WinRT
An introduction to WinRT
The evolution of WinRT
A little detail about WinJS
WinJS – its purpose and a distribution history
HTML5, CSS3, and JavaScript
WT with HTML5, CSS3, and JavaScript
The need for integrating promise with WT
Problems when using asynchronous programming
Jumpstarting promises
Writing a function that returns a promise
Error handling
Chaining promises using the then() and done() functions
Summary
6
Promises in Node.js
Promises in Node.js
The V8 engine – the mechanics
The V8 engine in Google Chrome
The evolution of Node.js
A brief introduction to Node.js
Download and install Node.js
Node Package Manager – NPM
Choice of environment
Setting up the environment for Node.js
A simple node server
Things we learned so far
Node.js with the Q library
Moving ahead with Q
Propagation in Q
Chaining and nesting promises
Sequences in Q
Combination in Q
How to handle errors in Q in Node.js
Making progress with promises
Getting to the end of a chain of promises
Callback-based promises versus Q-based promises
Q.Promise() – another way to create promises
Static methods of Q
Promise as a proxy
Familiarizing Node.js – the Q way
Unbinds and its solution
Q support for tracing stacks
Making promise-based actions
Object handling promises
View revisited
Aborting a promise
Q utilities for Node.js
Summary
7
Promises in Angular.js
Promises in Angular.js
The evolution of Angular.js
The structure of the Angular.js document
Getting started with Angular.js
Creating your first Angular.js file
How to use Angular.js on your local machine
What would be your preference for the server?
Key elements of Angular.js
Implementing promises in Angular.js
The schematics of using promises in Angular.js
Promise as a handle for callback
Blindly passing arguments and nested promises
Deferred objects or composed promises
Dealing with the nested calls
Concurrency in Angular.js
The combination of success and error
The safe approach
Route your promise
Summary
8
Promises in jQuery
Promises in jQuery
From where it started?
Behind the scenes – how does jQuery work?
Is your document ready to submit?
How to use jQuery
The syntax
Caching in jQuery
A sample example
JavaScript before and after jQuery
The solution – introducing promises in jQuery
Deferred in jQuery
$.Deferred().promise() in jQuery
Projecting a promise in jQuery
Joining promises with $.when
Your own $.Deferred process
The advent of promises in jQuery
Summary
9
JavaScript – The Future Is Now
JavaScript – The Future Is Now
ECMAScript 6 (ECMA 262)
harmony:generators
The MEAN stack
Real-time communication in JavaScript
Internet of Things
Computer animation and in 3D graphics
NoSQL databases
Summary
Index
Index

Promise

The beauty of working with JavaScript's asynchronous events is that the program continues its execution, even when it doesn't have any value it needs to work that is in progress. Such scenarios are named as yet known values from unfinished work. This can make working with asynchronous events in JavaScript challenging.

Promises are a programming construct that represents a value that is still unknown. Promises in JavaScript enable us to write asynchronous code in a parallel manner to synchronous code.

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