This example demonstrates how easing functions can animate bar chart updates in D3.js version 4.5.0. A static bar chart, built with SVG rectangles and text labels, initially displays a dataset of 20 values. Clicking the paragraph text triggers a two-second transition that updates all bars and labels with a new dataset, using the `d3.easeCircleIn` easing function to control the animation’s acceleration. The bar positions, heights, and colors are recalculated from the new data via linear and band scales.