This example visualizes a dynamic sine wave as a shifting field of circles, whose count and vertical positions oscillate continuously over time. Built with React and rendered as animated SVG, it uses D3’s `select`, `range`, and data join (`join('circle')`) to update circle positions every 10 milliseconds based on a time variable. The number of circles fluctuates between 0 and 200, while each circle’s y-coordinate follows a sine function that creates a flowing, wave-like motion across the screen.