A clickable red button triggers a randomized heatmap of up to one thousand points, where each point’s color interpolates from red to green based on its randomly generated value. The number of points and columns is recalculated on each click, and the heatmap cells are appended as SVG rectangles using D3.js and Underscore.js. When the button is clicked, new rectangles enter with a zero width and animate to full size, while exiting rectangles shrink to nothing, with staggered transitions creating a cascade effect. The animation uses D3’s `transition()` and `.delay()` to sequence the updates.