A simple bar chart renders three static rectangles from a hard-coded array of three values. The example demonstrates basic D3 data binding with `d3.select`, `canvas.selectAll`, and `.enter()`, appending SVG `rect` elements whose width and height are derived from each data point. The chart uses D3 v5 and outputs to an SVG canvas, with bars positioned vertically by index. No axes, scales, or interactivity are included, making it a minimal starter template for understanding core D3 joins.