Billboard.js 3.18.0 rolls out three major updates that sharpen chart interactivity. The new arc annotations let developers attach labels with lines outside pie, donut, gauge, and polar charts. Per‑group stack normalization fixes cross‑axis interference, while treemap label formatting now receives tile dimensions for smarter label placement.

Arc annotations replace the old label‑inside‑arc approach, pushing text to the outside and drawing a line back to its slice. This change improves readability on crowded charts and works across the four supported types. Developers can tweak line distance and visibility via the new `label.line` options.

Per‑group stack normalization addresses a long‑standing issue where `stack.normalize: true` summed all series, even those on the secondary y2 axis. By normalizing each group to 100 % independently, bar charts can now coexist with line series without distorting the visual scale. This is especially useful for dashboards that mix metrics.

The treemap label formatter now receives a `size` object with width and height in pixels, letting developers hide labels on tiles that are too small. This prevents clutter and keeps the hierarchy readable. The change aligns treemap rendering with other chart types that expose pixel dimensions for fine‑grained control.