This example demonstrates two custom legend components for mapping data values to visual encodings: a color legend for ordinal categories and a size legend for quantitative values. The color legend displays colored circles for fruits, while the size legend uses scaled circle radii to represent numeric values. Built with D3 v5, the code defines reusable functions `colorLegend` and `sizeLegend` that use `scaleOrdinal`, `scaleSqrt`, and selection joins to render SVG elements dynamically.