Search icon CANCEL
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Conferences
Free Learning
Arrow right icon
Learning TypeScript 2.x
Learning TypeScript 2.x

Learning TypeScript 2.x: Develop and maintain captivating web applications with ease , Second Edition

eBook
€22.99 €32.99
Paperback
€41.99
Subscription
Free Trial
Renews at €18.99p/m

What do you get with eBook?

Product feature icon Instant access to your Digital eBook purchase
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
Table of content icon View table of contents Preview book icon Preview Book

Learning TypeScript 2.x

Working with Types

In the preceding chapter, we learned some basic concepts about the TypeScript type system, including the basics about the type inference system and the optional static type annotations.

In this chapter, you will learn about the main features of the TypeScript type system, including the following concepts:

  • The line between TypeScript and JavaScript
  • The features of the type system
  • Union types, intersection types, and discriminated unions
  • Type aliases and local types
  • The typeof and keyof operators
  • Control flow analysis and type guards
  • Non-nullable types
  • Generic types
  • Mapped types, lookup types, and conditional types

The TypeScript type system's characteristics

In this section, we are going to learn about the main characteristics of the TypeScript type system, including concepts such as type inference, optional type annotation, and the differences between a nominal type system and a structural type system.

The line between TypeScript and JavaScript

One of the most important things that you are going to need to master to become a good TypeScript programmer is to be able to understand where TypeScript ends and JavaScript begins. It is very important to be able to understand what happens with our TypeScript code at three important phases:

  • Design time: This takes place when we are writing our TypeScript code and designing our application...

Core features of the TypeScript type system

In this section, we are going to learn about some of the core features of the TypeScript type system. This includes concepts such as union types, intersection guards, type guards, and type aliases.

Union types

TypeScript allows you to declare union types:

let path: string[]|string;
path = "/temp/log.xml";
path = ["/temp/log.xml", "/temp/errors.xml"];
path = 1; // Error

In the preceding example, we have declared a variable named path that can contain a single path (string) or a collection of paths (array of strings). In the example, we have also set the value of the variable. We assigned a string and an array of strings without errors; however, when we attempted...

Literal types

Literal types allow us to declare the exact value that a string Boolean or number must have. When we declare a variable using the let keyword, its value will be inferred as a primitive type:

let five = 5; // number
let falsy = false; // boolean
let shape = "rectangle"; // string

However, if we use the const keyword, the type is inferred as the actual assigned value:

const five = 5; // 5
const falsy = false; // false
const shape = "rectangle"; // rectangle

Literal types can be used in combination with union types, type guards, and type aliases with ease:

type ShapeKind = "square" | "rectangle" | "circle";

Literal types can be used in combination with type guards and the power of control flow analysis to narrow union types using a technique known as discriminated unions.

...

Advanced features of the TypeScript type system

In this section, we are going to learn some advanced type system features such as generic types, mapped types, and lookup types.

Generic types

Generic types can help us avoid using type casting and increase the reusability of our code by allowing us to declare (T) when a function, class, or method is consumed, as opposed to when it is declared:

function deserialize<T>(json: string): T {
return JSON.parse(json) as T;
}

interface User {
name: string;
age: number;
}

let user = deserialize<User>(`{"name":"Remo","age":28}`);

interface Rectangle {
width: number;
height: number;
}

let rectangle = deserialize<Rectangle>(`{&quot...

Summary

In this chapter, we learned about many of the features of the TypeScript type system. At this point, we should now have a good understanding of concepts such type inference, non-nullable types, structural typing, and control flow analysis.

In the next chapter, we will learn more about the usage of functions in TypeScript.

Left arrow icon Right arrow icon

Key benefits

  • Develop modular, scalable, maintainable, and adaptable web applications by taking advantage of TypeScript
  • Walk through the fundamentals of TypeScript with the help of practical examples
  • Enhance your web development skills using TypeScript 2.x

Description

TypeScript is an open source and cross-platform statically typed superset of JavaScript that compiles to plain JavaScript and runs in any browser or host. This book is a step-by-step guide that will take you through the use and benefits of TypeScript with the help of practical examples. You will start off by understanding the basics as well as the new features of TypeScript 2.x. Then, you will learn how to work with functions and asynchronous programming APIs. You will continue by learning how to resolve runtime issues and how to implement TypeScript applications using the Object-oriented programming (OOP) and functional programming (FP) paradigms. Later, you will automate your development workflow with the help of tools such as Webpack. Towards the end of this book, you will delve into some real-world scenarios by implementing some full-stack TypeScript applications with Node.js, React and Angular as well as how to optimize and test them. Finally, you will be introduced to the internal APIs of the TypeScript compiler, and you will learn how to create custom code analysis tools.

Who is this book for?

If you are a developer aiming to learn TypeScript to build attractive web applications, this book is for you. No prior knowledge of TypeScript is required. However, a basic understanding of JavaScript would be an added advantage.

What you will learn

  • Understand TypeScript in depth, including its runtime and advanced type system features
  • Master the core principles of the object-oriented programming and functional programming paradigms with TypeScript
  • Save time using automation tools such as Gulp, Webpack, ts-node, and npm scripts
  • Develop robust, modular, scalable, maintainable, and adaptable applications with testing frameworks such as Mocha, Chai, and Sinon.JS
  • Put your TypeScript skills to practice by developing full-stack web applications with Node.js, React and Angular
  • Use the APIs of the TypeScript compiler to build custom code analysis tool

Product Details

Country selected
Publication date, Length, Edition, Language, ISBN-13
Publication date : Apr 30, 2018
Length: 536 pages
Edition : 2nd
Language : English
ISBN-13 : 9781788396608
Languages :

What do you get with eBook?

Product feature icon Instant access to your Digital eBook purchase
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want

Product Details

Publication date : Apr 30, 2018
Length: 536 pages
Edition : 2nd
Language : English
ISBN-13 : 9781788396608
Languages :

Packt Subscriptions

See our plans and pricing
Modal Close icon
€18.99 billed monthly
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Simple pricing, no contract
€189.99 billed annually
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts
€264.99 billed in 18 months
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts

Frequently bought together


Stars icon
Total 115.97
TypeScript Microservices
€36.99
TypeScript 2.x By Example
€36.99
Learning TypeScript 2.x
€41.99
Total 115.97 Stars icon

Table of Contents

16 Chapters
Introducing TypeScript Chevron down icon Chevron up icon
Working with Types Chevron down icon Chevron up icon
Working with Functions Chevron down icon Chevron up icon
Object-Oriented Programming with TypeScript Chevron down icon Chevron up icon
Working with Dependencies Chevron down icon Chevron up icon
Understanding the Runtime Chevron down icon Chevron up icon
Functional Programming with TypeScript Chevron down icon Chevron up icon
Working with Decorators Chevron down icon Chevron up icon
Automating Your Development Workflow Chevron down icon Chevron up icon
Node.js Development with TypeScript Chevron down icon Chevron up icon
Frontend Development with React and TypeScript Chevron down icon Chevron up icon
Frontend Development with Angular and TypeScript Chevron down icon Chevron up icon
Application Performance Chevron down icon Chevron up icon
Application Testing Chevron down icon Chevron up icon
Working with the TypeScript Compiler and the Language Services Chevron down icon Chevron up icon
Other Books You May Enjoy Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Full star icon Empty star icon Empty star icon Empty star icon 2
(1 Ratings)
5 star 0%
4 star 0%
3 star 0%
2 star 100%
1 star 0%
Mr. T. Hamilton Jul 01, 2019
Full star icon Full star icon Empty star icon Empty star icon Empty star icon 2
I bought this book expecting a comprehensive look into Typescript, having very minimal experience with JavaScript. What I got was a book which felt to be hastily put together. The author has an idea of what he wants to talk about in each chapter, but instead of laying out a clear and coherent explanation of what he's trying to say, there's a rushed and scatter gun approach to explaining topics. The English quality is also not great, and the editing has allowed many typos to get in, which I think in itself speaks for the quality of this book.I would not recommend buying this book and instead looking at the official documentation, or reading one of the better JavaScript books then supplementing your knowledge with a brief overview of TypeScript elsewhere.
Amazon Verified review Amazon
Get free access to Packt library with over 7500+ books and video courses for 7 days!
Start Free Trial

FAQs

How do I buy and download an eBook? Chevron down icon Chevron up icon

Where there is an eBook version of a title available, you can buy it from the book details for that title. Add either the standalone eBook or the eBook and print book bundle to your shopping cart. Your eBook will show in your cart as a product on its own. After completing checkout and payment in the normal way, you will receive your receipt on the screen containing a link to a personalised PDF download file. This link will remain active for 30 days. You can download backup copies of the file by logging in to your account at any time.

If you already have Adobe reader installed, then clicking on the link will download and open the PDF file directly. If you don't, then save the PDF file on your machine and download the Reader to view it.

Please Note: Packt eBooks are non-returnable and non-refundable.

Packt eBook and Licensing When you buy an eBook from Packt Publishing, completing your purchase means you accept the terms of our licence agreement. Please read the full text of the agreement. In it we have tried to balance the need for the ebook to be usable for you the reader with our needs to protect the rights of us as Publishers and of our authors. In summary, the agreement says:

  • You may make copies of your eBook for your own use onto any machine
  • You may not pass copies of the eBook on to anyone else
How can I make a purchase on your website? Chevron down icon Chevron up icon

If you want to purchase a video course, eBook or Bundle (Print+eBook) please follow below steps:

  1. Register on our website using your email address and the password.
  2. Search for the title by name or ISBN using the search option.
  3. Select the title you want to purchase.
  4. Choose the format you wish to purchase the title in; if you order the Print Book, you get a free eBook copy of the same title. 
  5. Proceed with the checkout process (payment to be made using Credit Card, Debit Cart, or PayPal)
Where can I access support around an eBook? Chevron down icon Chevron up icon
  • If you experience a problem with using or installing Adobe Reader, the contact Adobe directly.
  • To view the errata for the book, see www.packtpub.com/support and view the pages for the title you have.
  • To view your account details or to download a new copy of the book go to www.packtpub.com/account
  • To contact us directly if a problem is not resolved, use www.packtpub.com/contact-us
What eBook formats do Packt support? Chevron down icon Chevron up icon

Our eBooks are currently available in a variety of formats such as PDF and ePubs. In the future, this may well change with trends and development in technology, but please note that our PDFs are not Adobe eBook Reader format, which has greater restrictions on security.

You will need to use Adobe Reader v9 or later in order to read Packt's PDF eBooks.

What are the benefits of eBooks? Chevron down icon Chevron up icon
  • You can get the information you need immediately
  • You can easily take them with you on a laptop
  • You can download them an unlimited number of times
  • You can print them out
  • They are copy-paste enabled
  • They are searchable
  • There is no password protection
  • They are lower price than print
  • They save resources and space
What is an eBook? Chevron down icon Chevron up icon

Packt eBooks are a complete electronic version of the print edition, available in PDF and ePub formats. Every piece of content down to the page numbering is the same. Because we save the costs of printing and shipping the book to you, we are able to offer eBooks at a lower cost than print editions.

When you have purchased an eBook, simply login to your account and click on the link in Your Download Area. We recommend you saving the file to your hard drive before opening it.

For optimal viewing of our eBooks, we recommend you download and install the free Adobe Reader version 9.