Book Image

Advanced TypeScript Programming Projects

By : Peter O'Hanlon
Book Image

Advanced TypeScript Programming Projects

By: Peter O'Hanlon

Overview of this book

With the demand for ever more complex websites, the need to write robust, standard-compliant JavaScript has never been greater. TypeScript is modern JavaScript with the support of a first-class type system, which makes it simpler to write complex web systems. With this book, you’ll explore core concepts and learn by building a series of websites and TypeScript apps. You’ll start with an introduction to TypeScript features that are often overlooked in other books, before moving on to creating a simple markdown parser. You’ll then explore React and get up to speed with creating a client-side contacts manager. Next, the book will help you discover the Angular framework and use the MEAN stack to create a photo gallery. Later sections will assist you in creating a GraphQL Angular Todo app and then writing a Socket.IO chatroom. The book will also lead you through developing your final Angular project which is a mapping app. As you progress, you’ll gain insights into React with Docker and microservices. You’ll even focus on how to build an image classification program with machine learning using TensorFlow. Finally, you’ll learn to combine TypeScript and C# to create an ASP.NET Core-based music library app. By the end of this book, you’ll be able to confidently use TypeScript 3.0 and different JavaScript frameworks to build high-quality apps.
Table of Contents (13 chapters)

Validating user inputs and the use of validators

At this stage, we really should think about validating inputs from the user. We are going to introduce two types of validation in our code. The first is the minimum length validation. In other words, we are going to ensure that some of the entries have to have a minimum number of entries before they can be considered to be valid. The second type of validation uses something called a regular expression to validate it. What this means is that it takes the input and compares it against a set of rules to see whether there is a match; the expressions can look a little bit odd if you are new to regular expressions, so we will break them down to see exactly what rules we are applying.

We are going to break our validation down into three parts:

  1. The classes that provide the checking features, such as applying a regular expression. We will...