Fork of Circles with D3
This example displays seven colored circles of varying sizes and positions on a pale green background. It demonstrates the D3 General update pattern for creating and managing SVG elements. The code uses `select`, `selectAll`, `data`, and `join` from D3 to bind circle data to SVG `<circle>` elements, then sets `cx`, `cy`, `r`, `fill`, and `opacity` attributes via method chaining. The data is an array of objects defining each circle's coordinates, radius, and color.