Chapter 2: Data Types and Variables

Overview

One of the main uses of computers is to process and display information. By processing we mean that the information is modified, interpreted, or filtered in some way by the computer. For example, on an online banking website, a customer may request details of all monies paid out from his account in the last month. Here the computer would retrieve the information, filter out any information not relating to payments made in the last month, and then display it in a web page. In some situations, information is processed without being displayed, and at other times, information is obtained directly without being processed. For example, in a banking environment, regular payments may be processed and transferred electronically without any human interaction or display.

In computing we refer to information as data. This data comes in all sorts of forms, such as numbers, text, dates, and times, to mention just a few. In this chapter, we'll be looking specifically at how JavaScript handles data, such as numbers and text. An understanding of how data is handled is fundamental to any programming language.

We start the chapter by looking at the various types of data JavaScript can process. Then we look at how we can store this data in the computer's memory so that we can use it again and again in the code. Finally, we see how to use JavaScript to manipulate and process the data.