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Mastering JavaScript Promises

By : Hussain

2.5 (2)

Mastering JavaScript Promises

2.5 (2)

By: Hussain

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.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Promises.js

1. 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

2. 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

3. 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

4. Implementing Promises

How to implement promises

Implementations in Java

Say hello to JDeferred

Mechanics of JDeferred

Ultimate JDeferred

Summary

5. Promises in WinRT

5. 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

6. 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

7. 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

8. 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

9. 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

Chapter 1. Promises.js

In today's world, computer programming languages are getting much more advanced and there is a shift in the approach of using technologies. This is due to the fact that technology has been emerging with the rapid change in businesses and their needs. The vast expansion of business on electronic devices has led universities, researchers, and industries to invest in generating the latest technologies and tools that result in the inception of many new computer languages.

However, this is not the case with JavaScript. It's relatively new. It has been used and dumped at least three times by the modern programming landscape and is now widely accepted as the tool to develop modern, scalable, and real-time web applications in today's cyberspace.

In the mid 90s, the era of dot-com was born and it was during this time when companies wanted to dominate the newly created market called cyberspace. Although this was a virtual place and had no physical existence, the war for dominance was at its peak. Netscape Communications Corporation wanted its own variant of a lightweight interpreted language that would complement Java by appealing to nonprofessional programmers. This task was given to Brendan Eich who developed the first version of JavaScript with the name "Mocha". Officially, it was called LiveScript when it was first released in September 1995 in Netscape's browser in beta version 2.0.

However, the name was changed to JavaScript when the version 2.0 B3 rolled out later. Since 1995, JavaScript has seen many ups and downs. There are stories of it being adopted, rejected, and adopted again. Soon after its launch, JavaScript gained a very popular response throughout the industry. Every major company contributed to its growth and used it after slight adjustment for their needs.

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