This example demonstrates two reusable legend components rendered as SVG: a color legend for ordinal data and a size legend for quantitative data. The color legend maps categorical values like "apple" and "lemon" to distinct colors, while the size legend uses d3.scaleSqrt to encode numeric ticks as proportional circle radii. Both legends are built with D3 v5 data joins, using selection.enter and merge to update groups, circles, and text. The code exports modular functions from colorLegend.js and sizeLegend.js, with styling applied via CSS classes like .tick.