This holds an array of numbers that are updated to represent a rolling sine wave. The entire array is mapped to one period of the sine wave, with the phase changing over time. Clicking the + button adds a point into the array (increasing the resolution). Clicking the - button removes a point.
The array is synchronised using d3 with an unordered list (showing synchronisation with HTML elements) and with an SVG path (showing the use of d3's scale and line functions). Adding and removing points is so you can see the enter, update, and exit sets for a very small example.