Book Image

Mastering TypeScript 3 - Third Edition

By : Nathan Rozentals
Book Image

Mastering TypeScript 3 - Third Edition

By: Nathan Rozentals

Overview of this book

TypeScript is both a language and a set of tools to generate JavaScript. It was designed by Anders Hejlsberg at Microsoft to help developers write enterprise-scale JavaScript. Starting with an introduction to the TypeScript language, before moving on to basic concepts, each section builds on previous knowledge in an incremental and easy-to-understand way. Advanced and powerful language features are all covered, including asynchronous programming techniques, decorators, and generics. This book explores many modern JavaScript and TypeScript frameworks side by side in order for the reader to learn their respective strengths and weaknesses. It will also thoroughly explore unit and integration testing for each framework. Best-of-breed applications utilize well-known design patterns in order to be scalable, maintainable, and testable. This book explores some of these object-oriented techniques and patterns, and shows real-world implementations. By the end of the book, you will have built a comprehensive, end-to-end web application to show how TypeScript language features, design patterns, and industry best practices can be brought together in a real-world scenario.
Table of Contents (16 chapters)
Free Chapter
TypeScript Tools and Framework Options

The Mediator pattern

Now that we can describe the various states that our UI is in, we can begin to apply the logic that is required to move between these states. We will use the Mediator pattern to accomplish this. The purpose of the Mediator pattern is to define how a set of objects interact with each other, and it does this by injecting an object in-between the ones that affect each other. This means that the objects in question do not actually communicate with each other, they work against an interface. This promotes loose coupling between objects.

There are essentially two parts to the Mediator pattern. The first part is to define an interface that the Mediator can call in order to apply the changes that it needs. The Mediator, in this case, is communicating with our UI classes. In our application, we will need the Mediator to be able to signal the UI to either show or hide...