This example shows a Sankey diagram with a custom modification to the link-drawing function in d3 v4. When two connected nodes share the same x position, their links curve in an S-shape instead of the standard arc. The layout is computed with d3.sankey(), using SVG rendering and drag-and-drop interactivity. Data comes from a JSON file, and the visualization colors nodes and weights links by flow value, with hover tooltips. The key code change is a single line in sankey.js’s link function: it checks whether the absolute difference between source and target x positions is less than the source node’s width, and if so, sets the curvature to -2 to create the S-curve; otherwise, it keeps the default curvature of 0.5. This fork builds on d3noob’s block for D3 v4.