This example demonstrates an interactive line chart of San Francisco weather data, allowing users to select variables for both the X and Y axes from dropdown menus and toggle between line and area chart display modes. The visualization renders temperature and precipitation measurements over time using an SVG canvas. Built with React and D3 v5, it employs `scaleTime` and `scaleLinear` for axis scaling, `line()` with `curveBasis` for path generation, and `axisBottom`/`axisLeft` for grid lines. A mouse-tracking tooltip displays the precise values at the cursor position.