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)

Objects


Objects are another way of handling data. In arrays the indexes are commonly numerical; objects give us a robust way of assigning and retrieving data. Objects are derived from the object-oriented programming concept; a programming paradigm that is very popular. Objects are a virtual representation of real-time data; they allow us to organize our data into logical groups via properties and methods. Properties describe the state of the object, while methods describe the behavior of the object. Properties are a key-value pair that holds the information. Take a look at the following:

In the previous example, we have instantiated a person object, and then added the firstname and lastname properties that described the object. We added behavior to the object by creating a method called getFullName, the method accessed the object properties, retrieved the data, and alerted the output onto the screen. In this example the properties are accessed by the dot notation; we could also access a property by putting the property name in square brackets similar to an array, but it is not popular. This is shown as follows:

The second way of creating an object is by using the curly braces. Here we are introduced to the this keyword, which provides a reference to the object's properties and methods, as shown in the following: