This example animates a growing wave of circles across the screen, with each circle’s size and vertical position modulated by a sine function over time. The circles are colored with a radial gradient that transitions from purple to white. Written in D3.js, the code uses `select`, `range`, and a join to append new circles each frame, while `transition` and `easeLinear` control the size change. The animation runs on a `setInterval` at 60fps, incrementally adding circles until they fill the viewport width, then resetting.