Book Image

Modern JavaScript Web Development Cookbook

By : Federico Kereki
Book Image

Modern JavaScript Web Development Cookbook

By: Federico Kereki

Overview of this book

JavaScript has evolved into a language that you can use on any platform. Modern JavaScript Web Development Cookbook is a perfect blend of solutions for traditional JavaScript development and modern areas that developers have lately been exploring with JavaScript. This comprehensive guide teaches you how to work with JavaScript on servers, browsers, mobile phones and desktops. You will start by exploring the new features of ES8. You will then move on to learning the use of ES8 on servers (with Node.js), with the objective of producing services and microservices and dealing with authentication and CORS. Once you get accustomed to ES8, you will learn to apply it to browsers using frameworks, such as React and Redux, which interact through Ajax with services. You will then understand the use of a modern framework to develop the UI. In addition to this, development for mobile devices with React Native will walk you through the benefits of creating native apps, both for Android and iOS. Finally, you’ll be able to apply your new-found knowledge of server-side and client-side tools to develop applications with Electron.
Table of Contents (15 chapters)

Testing changes with Snapshots

So far, we've been looking at automatic tests for components, events, and actions, so let's end this chapter by considering a testing tool that isn't really a part of TDD, but rather a safeguard against unwanted or unexpected changes after the fact: snapshots. (In TDD, tests would be written before coding the component, but you'll see that this is impossible here.) Snapshot tests work like this: you render a UI component, capture what HTML was produced, and then that is compared to a reference capture that was previously stored. If both captures do not match, either somebody made an unexpected change or the change was actually expected. If this is the case, you'll have to verify that the new capture is correct and then drop the old one.

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