Book Image

Learning Angular - Fourth Edition

By : Aristeidis Bampakos, Pablo Deeleman
5 (1)
Book Image

Learning Angular - Fourth Edition

5 (1)
By: Aristeidis Bampakos, Pablo Deeleman

Overview of this book

As Angular continues to reign as one of the top JavaScript frameworks, more developers are seeking out the best way to get started with this extraordinarily flexible and secure framework. Learning Angular, now in its fourth edition, will show you how you can use it to achieve cross-platform high performance with the latest web techniques, extensive integration with modern web standards, and integrated development environments (IDEs). The book is especially useful for those new to Angular and will help you to get to grips with the bare bones of the framework to start developing Angular apps. You'll learn how to develop apps by harnessing the power of the Angular command-line interface (CLI), write unit tests, style your apps by following the Material Design guidelines, and finally, deploy them to a hosting provider. Updated for Angular 15, this new edition covers lots of new features and tutorials that address the current frontend web development challenges. You’ll find a new dedicated chapter on observables and RxJS, more on error handling and debugging in Angular, and new real-life examples. By the end of this book, you’ll not only be able to create Angular applications with TypeScript from scratch, but also enhance your coding skills with best practices.
Table of Contents (17 chapters)
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The history of TypeScript

Transforming small web applications into thick monolithic clients was impossible due to the limitations of earlier JavaScript versions, such as the ECMAScript 5 specification. In a nutshell, large-scale JavaScript applications suffered from serious maintainability and scalability problems as soon as they grew in size and complexity. This issue became more relevant as new libraries and modules required seamless integration into our applications. The lack of proper mechanisms for interoperability led to cumbersome solutions that never seemed to fit the bill.

As a response to these concerns, ECMAScript 6 (also known as ES6 or ES2015) promised to solve these issues by introducing better module loading functionalities, an improved language architecture for better scope handling, and a wide variety of syntactic sugar to better manage types and objects. Class-based programming introduced an opportunity to embrace a more Object-Oriented Programming (OOP) approach when building large-scale applications.

Microsoft took on this challenge and spent nearly two years building a superset of the language, combining the conventions of ES6 and borrowing some proposals from the next specification version. The idea was to launch something that would help build enterprise applications with a lower error footprint using static type checking, better tooling, and code analysis. After two years of development led by Anders Hejlsberg, lead architect of C# and creator of Delphi and Turbo Pascal, TypeScript 0.8 was finally introduced in 2012 and reached version 1.0 2 years later. It was not only running ahead of ES6 but also implemented the same features and provided a stable environment for building large-scale applications. It introduced, among other features, optional static typing through type annotations, thereby ensuring type checking at compile time and catching errors early in the development process. Its support for declaration files also enabled developers to describe the interface of their modules so that other developers could better integrate them into their code workflow and tooling.

The benefits of TypeScript

As a superset of JavaScript, one of the main advantages of embracing TypeScript in your next project is the low entry barrier. If you know JavaScript, you are pretty much all set since all the additional features in TypeScript are optional. You can pick and introduce any of them to achieve your goal. Overall, there is a long list of solid arguments for advocating TypeScript in your next project, and all of them apply to Angular as well.

Here is a short rundown, to name a few:

  • Annotating your code with types ensures a consistent integration of your different code units and improves code readability and comprehension.
  • The built-in type-checker analyzes your code at compile time and helps you prevent errors before executing your code.
  • The use of types ensures consistency across your application. Combined with the previous two, the overall code error footprint gets minimized in the long run.
  • TypeScript extends classes with long-time demanded features such as class fields, private members, and enumerations.
  • Decorators allow you to extend your classes and implementations in unique ways.
  • Interfaces ensure a smooth and seamless integration of your libraries in other systems and code bases.
  • TypeScript support across different IDEs is terrific, and you can benefit from features such as highlighting code, real-time type checking, and automatic compilation at no cost.
  • The syntax is familiar to developers coming from other OOP-based backgrounds such as Java, C#, and C++.

Introducing TypeScript resources

Let’s have a look at where we can get further support to learn and test-drive our new knowledge of TypeScript.

In this book, we will be using TypeScript 4.8 as it is supported by Angular 15.

The official website

Our first stop is the official website of the language at

It contains extensive language documentation and a playground that gives us access to a quick tutorial to get up to speed with the language in no time. It includes some ready-made code examples that cover some of the most common traits of the language. We encourage you to leverage this tool to test the code examples we cover throughout this chapter.

The official wiki documentation

The code for TypeScript is fully open-sourced at GitHub, and the Microsoft team has put reasonable effort into documenting the different facets of the code in the wiki available on the repository site. We encourage you to take a look at it any time you have a question or if you want to dive deeper into any of the language features or form aspects of its syntax. The wiki is located at

In the following section, we will introduce the typing system of TypeScript. We will explore the most basic types of the TypeScript language. We will also learn how to benefit from the typing system and create custom and dynamic types to enhance our applications further.