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)

Writing test for pipes

Writing test cases for pipes is one of the easiest examples we can use to get started. The primary reason for this is that normally, pipes don't have external dependencies, which allows us to easily test the code logic without the worry of mocking.

We have one pipe function in our Sample Trello application, custom sort, so we will be writing test cases for this. You can review the custom sort code from our previous chapter, or look it up in https://github.com/sachinohri/SampleTrelloApplication.

Creating a new file

To write our test case, let's first create a new file in the same folder where we have the custom sort code. Let's name our file custom-sort.pipe.spec.ts. The logic in our...