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)

Validating JSON

Similar to our debugging resources, there are a lot of popular web tools that help us with validating JSON that we build. JSONLint is one of the most popular web tools that are available for validating our JSON feeds.


When we are using a server-side program such as PHP, Python, or Java, the built-in JSON encoding libraries generate the JSON feed, and normally the feed will be a valid JSON feed.

JSONLint has a very straightforward interface that allows the user to paste the JSON they want to validate, and returns either a success message or an error message based on the JSON feed that we paste. Let us begin by validating a bad piece of JSON to see the error message that would be returned, and then let us fix it to view the success message. For this example, I will copy the students feed from the previous example, and add a trailing comma at the end of the second element:

Notice that we have added a trailing comma to the last item in our JSON object, and the best part about...