A sequence of blue circles enters, shifts to green, and updates to orange as the dataset grows and shrinks over time; circles removed from the data turn red before disappearing. This animation demonstrates how D3 v5’s `selectAll`, `exit`, and `enter` selections handle data changes, using svg transitions with a 700-millisecond duration for updates and 500-millisecond for exits. The underlying data is a simple array of x-coordinates, rendered as SVG circles with a fixed y-coordinate and radius, driven by timed `render` calls in a static HTML page.