Book Image

Object-Oriented JavaScript - Second Edition

Book Image

Object-Oriented JavaScript - Second Edition

Overview of this book

JavaScript is the behavior, the third pillar in today's paradigm that looks at web pages as something that consists of clearly distinguishable parts: content (HTML), presentation (CSS) and behavior (JavaScript). Using JavaScript, you can create not only web pages but also desktop widgets, browser and application extensions, and other pieces of software. It's a pretty good deal: you learn one language and then code all kinds of different applications. While there's one chapter specifically dedicated to the web browser environment including DOM, Events and AJAX tutorials, the rest is applicable to the other environments Many web developers have tried coding or adopting some bits of JavaScript, but it is time to "man up" and learn the language properly because it is the language of the browser and is, virtually, everywhere. This book starts from zero, not assuming any prior JavaScript programming knowledge and takes you through all the in-depth and exciting futures hidden behind the facade. Once listed in the "nice to have" sections of job postings, these days the knowledge of JavaScript is a deciding factor when it comes to hiring web developers. After reading this book you'll be prepared to ace your JavaScript job interview and even impress with some bits that the interviewer maybe didn't know. You should read this book if you want to be able to take your JavaScript skills to a new level of sophistication.
Table of Contents (19 chapters)
Object-Oriented JavaScript Second Edition
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
Built-in Functions
Regular Expressions
Index

XMLHttpRequest


XMLHttpRequest() is an object (a constructor function) that allows you to send HTTP requests from JavaScript. Historically, XMLHttpRequest (or XHR for short) was introduced in IE and was implemented as an ActiveX object. Starting with IE7 it's a native browser object, the same way as it's in the other browsers. The common implementation of this object across browsers gave birth to the so-called Ajax applications, where it's no longer necessary to refresh the whole page every time you need new content. With JavaScript, you can make an HTTP request to the server, get the response, and update only a part of the page. This way you can build much more responsive and desktop-like web pages.

Ajax stands for Asynchronous JavaScript and XML .

  • Asynchronous because after sending an HTTP request your code doesn't need to wait for the response, but it can do other stuff and be notified (through an event) when the response arrives.

  • JavaScript because it's obvious that XHR objects are created...