Book Image

TypeScript Design Patterns

By : Vilic Vane
Book Image

TypeScript Design Patterns

By: Vilic Vane

Overview of this book

In programming, there are several problems that occur frequently. To solve these problems, there are various repeatable solutions that are known as design patterns. Design patterns are a great way to improve the efficiency of your programs and improve your productivity. This book is a collection of the most important patterns you need to improve your applications’ performance and your productivity. The journey starts by explaining the current challenges when designing and developing an application and how you can solve these challenges by applying the correct design pattern and best practices. Each pattern is accompanied with rich examples that demonstrate the power of patterns for a range of tasks, from building an application to code testing. We’ll introduce low-level programming concepts to help you write TypeScript code, as well as work with software architecture, best practices, and design aspects.
Table of Contents (15 chapters)
TypeScript Design Patterns
About the Author
About the Reviewer

State Pattern

It's possible for some objects to behave completely differently when they are in different states. Let's think about an easy example first. Consider rendering and interacting with a custom button in two states: enabled and disabled. When the button is enabled, it lights up and changes its style to active on a mouse hover, and of course, it handles clicks; when disabled, it dims and no longer cares about mouse events.

We may think of an abstraction with two operations: render (with a parameter that indicates whether the mouse is hovering) and click; along with two states: enabled and disabled. We can even divide deeper and have state active, but that won't be necessary in our case.

And now we can have StateEnabled with both render and click methods implemented, while having StateDisabled with only render method implemented because it does not care about the hover parameter. In this example, we are expecting every method of the states being callable. So we can have the abstract...