This example demonstrates the general update pattern for D3 legends, showing color and size legends built with ordinal and sequential scales. The color legend maps fruit names to colors using `scaleOrdinal`, while the size legend displays tick values from a `scaleSqrt` with circles sized proportionally. Both legends use D3’s enter, merge, and exit selections to handle dynamic updates, with circles and text appended to group elements. The SVG rendering shows the pattern’s special cases: handling elements that only appear on update, and managing nested selections within each data-bound group.