Chapter 10 — Charts with Chart.js

New concepts: Chart.js, bar chart, line chart, dynamic updates

Open the browser Console (F12 → Console) to see output from console.log().

Exercises

1. Build a bar chart: revenue per region from the sales data
2. Add a line chart: monthly revenue trend (group by month)
3. Add a click handler on chart bars to filter the table below
4. Add a 'Refresh' button that re-fetches data and updates the chart