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

Communicating with the server


Many people use third-party libraries to make any request to a server. But do we need these libraries? Let's examine in the following how AJAX can be used natively and what will be the next communication API.

XHR

XMLHttpRequest (XHR) is the main API in JavaScript to exchange data between client and server. XHR was firstly presented by Microsoft in IE5 via ActiveX (1999) and had a proprietary syntax in IE browser until version 7 (2006). This led to compatibility issues that called forth the rise of AJAX-libraries such as Prototype and jQuery. Today, support for XHR is consistent across all the major browsers. In general, to perform an HTML or HTTPS request, we have to do a number of tasks. We create an instance of XHR, initialize a request via open method, subscribe listeners to request-dependent events, set request headers (setRequestHeader), and eventually call the send method:

var xhr = new XMLHttpRequest();
xhr.open( "GET", "http://www.telize.com/jsonip?callback...