Bars transition over text shows a row of colored bars repeatedly rising and falling while the letter inside each bar toggles between two hidden messages. Using D3.js 3.5.5, ordinal and linear scales map letter positions and bar heights, while a custom recursive transition drives each bar’s vertical movement and color change. The code builds an SVG with text elements and rects, animating them via `transition().duration(1000).delay(...).each(slide)`, swapping between the letters arrays on each cycle. The bars cycle through a color scale, and the text flips between "Item explorer" and "by Michael Ankerst" as the animation loops.