Book Image

TypeScript 4 Design Patterns and Best Practices

By : Theofanis Despoudis
Book Image

TypeScript 4 Design Patterns and Best Practices

By: Theofanis Despoudis

Overview of this book

Design patterns are critical armor for every developer to build maintainable apps. TypeScript 4 Design Patterns and Best Practices is a one-stop guide to help you learn design patterns and practices to develop scalable TypeScript applications. It will also serve as handy documentation for future maintainers. This book takes a hands-on approach to help you get up and running with the implementation of TypeScript design patterns and associated methodologies for writing testable code. You'll start by exploring the practical aspects of TypeScript 4 and its new features. The book will then take you through the traditional gang of four (GOF) design patterns in their classic and alternative form and show you how to use them in real-world development projects. Once you've got to grips with traditional design patterns, you'll advance to learning about their functional programming and reactive programming counterparts and how to couple them to deliver better and more idiomatic TypeScript code. By the end of this TypeScript book, you'll be able to efficiently recognize when and how to use the right design patterns in any practical use case and gain the confidence to work on scalable and maintainable TypeScript projects of any size.

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Table of Contents (14 chapters)
Preface
Preface
Who this book is for
What this book covers
To get the most out of this book
Download the example code files
Download the color images
Conventions used
Get in touch
Share your thoughts
1
Section 1: Getting Started with TypeScript 4
Section 1: Getting Started with TypeScript 4
Free Chapter
2
Chapter 1: Getting Started with Typescript 4
Chapter 1: Getting Started with Typescript 4
Technical requirements
Introducing TypeScript 4
Understanding TypeScript and JavaScript's relationship
Installing and using the code examples
Using VSCode with TypeScript
Introducing Unified Modeling Language (UML)
Summary
Q & A
Further reading
3
Chapter 2: TypeScript Core Principles
Chapter 2: TypeScript Core Principles
Technical requirements
Working with advanced types
OOP with TypeScript
Developing in the browser
Developing in the server
Introducing design patterns in TypeScript
Summary
Q&A
Further reading
4
Section 2: Core Design Patterns and Concepts
Section 2: Core Design Patterns and Concepts
5
Chapter 3: Creational Design Patterns
Chapter 3: Creational Design Patterns
Technical requirements
Creational design patterns
Singleton pattern
Prototype pattern
Builder pattern
Factory method pattern
Abstract Factory pattern
Summary
Q&A
Further reading
6
Chapter 4: Structural Design Patterns
Chapter 4: Structural Design Patterns
Technical requirements
Understanding structural design patterns
Adapter pattern
Decorator pattern
Façade pattern
Composite pattern
Proxy pattern
Bridge pattern
Flyweight pattern
Summary
Q&A
Further reading
7
Chapter 5: Behavioral Design Patterns
Chapter 5: Behavioral Design Patterns
Technical requirements
Behavioral design patterns
The Strategy pattern?
Chain of Responsibility
The Command pattern
The Iterator pattern
The Mediator pattern
The Observer pattern
The Memento pattern
The State pattern
The Template method pattern
The Visitor pattern
Summary
Q&A
Further reading
8
Section 3: Advanced Concepts and Best Practices
Section 3: Advanced Concepts and Best Practices
9
Chapter 6: Functional Programming with TypeScript
Chapter 6: Functional Programming with TypeScript
Technical requirements
Learning key concepts in functional programming
Understanding functional lenses
Understanding transducers
Understanding monads
Summary
Q & A
Further reading
10
Chapter 7: Reactive Programming with TypeScript
Chapter 7: Reactive Programming with TypeScript
Technical requirements
Learning Reactive programming concepts
The asynchronous propagation of changes
Understanding Promises and Futures
Learning observables
Summary
Q & A
Further reading
11
Chapter 8: Developing Modern and Robust TypeScript Applications
Chapter 8: Developing Modern and Robust TypeScript Applications
Technical requirements
Combining patterns
Using utility types
Using domain-driven design
Applying the SOLID principles
Summary
Q&A
Further reading
12
Chapter 9: Anti-Patterns and Workarounds
Chapter 9: Anti-Patterns and Workarounds
Technical requirements
Class overuse
Not using runtime assertions
Permissive or incorrect types
Using idiomatic code from other languages
Type inference gotchas
Summary
Q & A
Further reading
Why subscribe?
13
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The Template method pattern

The Template method pattern is used to define a basic template of an algorithm and have subclasses override specific steps at runtime. This means that you have a series of steps in an algorithm but you want to consider having placeholder calls that delegate the logic to subclasses. Depending on the result, the algorithm behaves differently, which means that this pattern leverages inheritance to provide specialization.

You mainly want to employ this pattern because it can get very repetitive to create similar methods that perform the same operation, such as checking a specific state variable, but differ in some aspects. Let's explain in detail when to use this pattern.

When to use the Template method pattern?

You want to use this pattern when faced with the following problems:

  • You need to keep parts of an algorithm or a process the same but have some methods implement the specialized behavior: The basic steps of the algorithm are the...
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