Book Image

JavaScript and JSON Essentials

By : Sai S Sriparasa
Book Image

JavaScript and JSON Essentials

By: Sai S Sriparasa

Overview of this book

The exchange of data over the Internet has been carried out since its inception. Delimiter-separated lists such as CSV and tag-separated languages such as XML are very popular, yet they are considered to be verbose by a section of developers. JSON (JavaScript Object Notation) is a lightweight text-based code to create objects to transfer data over the Internet. It is a data exchange format that is human-readable (like XML, but without the markup around your actual payload) and its syntax is a subset of the JavaScript language that was standardized in 1999. JavaScript and JSON Essentials is a step-by-step guide that will introduce you to JSON and help you understand how the lightweight JSON data format can be used in different ways either to store data locally or to transfer data over the Internet. This book will teach you how to use JSON effectively with JavaScript. This book begins with a brief refresher course on JavaScript before taking you through how JSON data can be transferred via synchronous, asynchronous, and cross-domain asynchronous HTTP calls. JSON is not just about data transfer; this book throws light on the alternate implementations of JSON as well. You will learn the data types that JavaScript uses and how those data types can be used in JSON. You will go through the concepts of how to create, update, parse, and delete a JSON object. You will also look at the different techniques of loading a JSON file onto a web page, how to use jQuery to traverse through an object, and how to perform access operations. You will also go over a few resources that will make debugging JSON quick and easy.
Table of Contents (15 chapters)

Implementing JSONP


We are using the same URL as before to fetch the data, but we have added the jsonp parameter and are setting it to getRedditData; it is important to note that the feed is now padded into our callback getRedditData. Now let's replace the URL property in our earlier script to create a new script that will fetch us the JSON feed.

A few properties such as url and dataType have been modified and a few new properties such as contentType and jsonpCallback have been added. We have already discussed the change in the url property, so let us look at the other properties.

Earlier, the dataType property was set to json as the incoming feed was of type json, but now the JSON feed is being padded into a callback, and it has to be switched so that the browser expects a callback rather than JSON itself. The new properties that have been added are contentType and jsonpCallback; the property contentType specifies the type of content being sent to the web server. jsonpCallback takes the name...