This chapter covered the most important module in the D3 library: d3-selection, which provides a flow-based DSL for selecting DOM elements, binding them to data, and updating their properties after the data changes. Most of the methods in this library were used in examples that explored the general update pattern, which is a fundamental concept used in practically all D3 applications that should be very well understood. This chapter also introduced the selection.join() method, which is a modern and simpler alternative to the general update pattern.
You also learned how to load external files and parse popular data formats, such as CSV and JSON, using methods from the d3-dsv and d3-fetch modules.
There's still a lot to learn before mastering D3. In the next chapter, you will continue to use most of the methods from this chapter, and learn how to use some new tools...