Book Image

Test-Driven JavaScript Development

By : Ravi Kumar Gupta
Book Image

Test-Driven JavaScript Development

By: Ravi Kumar Gupta

Overview of this book

Initially, all processing used to happen on the server-side and simple output was the response to web browsers. Nowadays, there are so many JavaScript frameworks and libraries created that help readers to create charts, animations, simulations, and so on. By the time a project finishes or reaches a stable state, so much JavaScript code has already been written that changing and maintaining it further is tedious. Here comes the importance of automated testing and more specifically, developing all that code in a test-driven environment. Test-driven development is a methodology that makes testing the central part of the design process – before writing code developers decide upon the conditions that code must meet to pass a test. The end goal is to help the readers understand the importance and process of using TDD as a part of development. This book starts with the details about test-driven development, its importance, need, and benefits. Later the book introduces popular tools and frameworks like YUI, Karma, QUnit, DalekJS, JsUnit and goes on to utilize Jasmine, Mocha, Karma for advanced concepts like feature detection, server-side testing, and patterns. We are going to understand, write, and run tests, and further debug our programs. The book concludes with best practices in JavaScript testing. By the end of the book, the readers will know why they should test, how to do it most efficiently, and will have a number of versatile tests (and methods for devising new tests) to get to work immediately.
Table of Contents (16 chapters)
Test-Driven JavaScript Development
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Understanding feature detection


Days are gone when there were simple JavaScript codes utilizing limited browser features, and a website would not be very complex. These days, a developer needs canvas, audio and video, geographic location of the user, drag and drop, and many more features to implement all needed requirements. Unfortunately, not all browsers support all of these features in their latest versions.

In case a feature is not supported, a developer writes a cross-browser script, which either first detects a browser or if a feature is present, and then executes suitable code for that browser. This task is very challenging as detecting a browser is not always reliable. You detect a browser, and then make an assumption that the feature will be present, which might not always be correct. An older version of browser may not support a feature or a newer version may drop a feature. You will learn about browser detection and why it is not a good practice later in this chapter.

The other...