Fork of D3 Transitions*
Six colored circles expand from zero to their full radius on a pale green background. The animation uses d3.transition with two different speeds: a slow two-second ease for entrance and exit, and a fast half-second linear ease for updates. Circle data is stored in a local array with id, x, y, radius, and fill values. The code uses d3.select, data joins, and transition().delay() to stagger the growing circles, while exit transitions shrink them back to zero before removal.