Book Image

Angular 2 Cookbook

By : Patrick Gillespie, Matthew Frisbie
Book Image

Angular 2 Cookbook

By: Patrick Gillespie, Matthew Frisbie

Overview of this book

Angular 2 introduces an entirely new way to build applications. It wholly embraces all the newest concepts that are built into the next generation of browsers, and it cuts away all the fat and bloat from Angular 1. This book plunges directly into the heart of all the most important Angular 2 concepts for you to conquer. In addition to covering all the Angular 2 fundamentals, such as components, forms, and services, it demonstrates how the framework embraces a range of new web technologies such as ES6 and TypeScript syntax, Promises, Observables, and Web Workers, among many others. This book covers all the most complicated Angular concepts and at the same time introduces the best practices with which to wield these powerful tools. It also covers in detail all the concepts you'll need to get you building applications faster. Oft-neglected topics such as testing and performance optimization are widely covered as well. A developer that reads through all the content in this book will have a broad and deep understanding of all the major topics in the Angular 2 universe.
Table of Contents (18 chapters)
Angular 2 Cookbook
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Dedication
Preface

Chaining Promises and Promise handlers


Much of the purpose of promises is to allow the developer to serialize and reason about independent asynchronous actions. This can be accomplished by utilizing the Promise chaining feature.

Note

The code, links, and a live example of this are available at http://ngcookbook.herokuapp.com/6828/ .

How to do it...

The promise handler definition method then() returns another promise, which can have further handlers defined upon it—in a handler called chain:

var successHandler = () => { console.log('called'); }; 
 
var p = new Promise((resolve, reject) => { resolve(); }) 
  .then(successHandler) 
  .then(successHandler) 
  .then(successHandler); 
 
// called 
// called 
// called 

Chained handlers' data handoff

Chained handlers can pass data to their subsequent handlers in the following manner:

var successHandler = (val) => {  
  console.log(val);  
  return val+1; 
}; 
 
var p...