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)

Accessing objects in JSON

Now that we understand how to make a script call to fetch an external JavaScript file, let us use the same technique to import a JSON feed. I have generated a test employee JSON data feed with 100 records. To traverse through any JSON feed, it is important to make a note of how the data is arranged. The keys in this data feed are basic employee information such as employee number, date of birth, first name, last name, gender, hire date, titles that they have held, and the dates during which they have held those titles. A few employees have held the same title throughout their tenure, while there are some employees who have held more than one title.


This JSON file will be part of the code files for exercises.

As we are dealing with a complex JSON data feed, let us save the data feed to a file. In the data_json_feed.html file, we have imported the data.json file, which is in the same folder as the HTML file. It is noteworthy that the JSON feed has been assigned...