In this chapter, we used the drag behavior and the reusable chart pattern to create a slider control. This control can be used to allow users to select values within a range. We used the slider component to create a color picker for the Lab color space. In the implementation of the color picker, we didn't need to know about the internals of the slider; we only used the slider's public interface. The composition between reusable components allows us to create rich components without having to handle the details of their internal elements.

In the next chapter, we will learn how to create tooltips for our charts and how to implement more advanced user interface components. We will also create an area chart that allows us to measure variations between two points in the chart by using brushing.