Chained Transitions II
The visualization shows a vertical column of 50 black circles that move in a choreographed wave, sliding horizontally across the screen and then returning, one after another. The animation uses chained transitions to create a continuous looping sequence. Built with D3 v4, it employs `d3.active` to manage each circle’s transition chain, with `d3.scalePoint` positioning the circles vertically and `d3.scaleLinear` mapping the color gradient from yellow to blue based on the circle’s index. The code uses SVG circle elements and CSS styling, with each circle’s fill determined by its position in the modulo sequence.