- Adopt ES2015, including support for iterables and collections (Map and Set).
- Remove d3.event; selection.on now passes events directly to listeners.
- Remove d3.mouse, d3.touch, d3.touches, d3.clientPoint; add d3.pointer and d3.pointers.
- Remove d3.nest; add d3.group and d3.rollup.
- Remove d3-collection; see d3-array.
- Remove d3-voronoi; add d3-delaunay.
- Remove support for Bower.
For more on what’s new, see CHANGES.
To upgrade from D3 5.x, see the migration guide.