d3 learning
This example shows a simple bar chart where 100 vertical bars fill the width of an SVG canvas, each bar representing an index from 0 to 99. The chart is rendered using React with the D3 library, specifically using `d3.select`, `d3.range`, and the `join` method to bind data and create the rectangles. The SVG elements are appended directly to the document body, with bars positioned horizontally at intervals of 20 pixels and a fixed height of 500 pixels.