This example shows a simple bar chart built with D3.js that updates when new data arrives after two seconds. The visualization uses an SVG container with six steelblue rectangles, demonstrating D3’s data join pattern. The code applies `svg.selectAll('rect')`, `data()`, `enter()`, and `exit()` selections to handle dynamic updates, with `setTimeout` triggering a change from the initial array [4, 8, 15, 16, 23, 42] to a five-element dataset. Bars are positioned and sized using the `attr` method based on array values.