In Chapter 4, Creating a Bar Graph, you learned how to create a bar graph that was based upon a sequence of integers that were statically coded within the application. Although the resulting graph looks quite nice, there are several issues with the way the data is provided and rendered.

One of the issues is that the data is hard-coded within the application. Almost invariably, we are going to load the data from an external source. D3.js provides a rich set of functionalities for loading data from sources over the web, and which is represented in different formats. In this chapter, you will learn to use D3.js for loading data from the web in JSON, CSV, and TSV formats.

A second issue with the data in the example given in the previous chapter was that it was simply an array of integers. Data will often be represented as collections of objects with multiple properties, many of which we do not need for our visualization. They are also often represented as strings...