Book Image

Javascript Unlocked

Book Image

Javascript Unlocked

Overview of this book

JavaScript stands bestride the world like a colossus. Having conquered web development, it now advances into new areas such as server scripting, desktop and mobile development, game scripting, and more. One of the most essential languages for any modern developer, the fully-engaged JavaScript programmer need to know the tricks, non-documented features, quirks, and best practices of this powerful, adaptive language. This all-practical guide is stuffed with code recipes and keys to help you unlock the full potential of JavaScript. Start by diving right into the core of JavaScript, with power user techniques for getting better maintainability and performance from the basic building blocks of your code. Get to grips with modular programming to bring real power to the browser, master client-side JavaScript scripting without jQuery or other frameworks, and discover the full potential of asynchronous coding. Do great things with HTML5 APIs, including building your first web component, tackle the essential requirements of writing large-scale applications, and optimize JavaScript’s performance behind the browser. Wrap up with in-depth advice and best practice for debugging and keeping your JavaScript maintainable for scaling, long-term projects. With every task demonstrated in both classic ES5 JavaScript and next generation ES6-7 versions of the language, Whether read cover-to-cover or dipped into for specific keys and recipes, JavaScript Unlocked is your essential guide for pushing JavaScript to its limits.
Table of Contents (15 chapters)
JavaScript Unlocked
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Learning to use server-to-browser communication channels


Using XHR or Fetch API, we can request a state from the server. This is a one-way communication. If we want real-time communication, we need this in the opposite direction as well. For example, we may want user notifications (your post has been liked, new comment, or new private message) to pop up as soon as the corresponding records change in the DB. The server side has connection to the DB, so we expect the server to notify the client. In the past, to receive these events on the client, we were using tricks that were known under the umbrella term COMET (hidden iframe, long polling, tag long polling, and others). Now we can go with native JavaScript APIs.

Server-Sent Events

The technology that provides a way to subscribe to server-side events is the Server-Sent Events (SSE) API. On the client, we register a server stream (EventSource) and subscribe to the event coming from it:

var src = new EventSource( "./sse-server.php" );

src.addEventListener...