Animated bar chart
This example demonstrates how to build an animated bar chart using D3 version 4. The visualization first draws a static cartoon-like figure composed of SVG shapes (rectangles, circles, and lines) to serve as a backdrop, then relies on a separate JavaScript file (index.js) to generate the chart’s dynamic elements. The code explicitly uses D3’s selection and arc APIs, including `d3.select` and `d3.arc()`, to construct the scene, with the bar chart itself styled via CSS classes such as `.bar` and `.highlight`.