Book Image

TypeScript 2.x By Example

By : Sachin Ohri
Book Image

TypeScript 2.x By Example

By: Sachin Ohri

Overview of this book

The TypeScript language, compiler, and open source development toolset brings JavaScript development up to the enterprise level. It allows you to use ES5, ES6, and ES7 JavaScript language features today, including classes, interfaces, generics, modules, and more. Its simple typing syntax enables building large, robust applications using object-oriented techniques and industry-standard design principles. This book aims at teaching you how to get up and running with TypeScript development in the most practical way possible. Taking you through two exciting projects built from scratch, you will learn the basics of TypeScript, before progressing to functions, generics, promises, and callbacks. Then, you’ll get to implement object-oriented programming as well as optimize your applications with effective memory management. You’ll also learn to test and secure your applications, before deploying them. Starting with a basic SPA built using Angular, you will progress on to building, maybe, a Chat application or a cool application. You’ll also learn how to use NativeScript to build a cool mobile application. Each of these applications with be explained in detail, allowing you to grasp the concepts fast. By the end of this book, you will have not only built two amazing projects but you will also have the skills necessary to take your development to the next level.
Table of Contents (11 chapters)


Functions are the building blocks of the JavaScript programming language, which allow us to write readable, maintainable, and reusable code. Functions define the action to be performed. If you have done any JavaScript development you would have written functions. TypeScript functions are not very different from JavaScript functions, with the addition of some new features that allow us to write code that is more understandable and error-free.

Here is an example of how a TypeScript function is defined:

function printFullName(firstName:string,lastName:string):string{
return firstName + " " + lastName;

This example shows how a function is defined in TypeScript. We have a function keyword, which is prefixed to the function name, followed by a list of parameters. In TypeScript, we mostly use functions inside classes as methods, with one difference that the function...