This example demonstrates how d3.scaleThreshold() maps continuous numeric values to discrete color bins. A d3.scaleLinear() positions 60 rectangles along the x-axis, while the threshold scale assigns one of four fill colors—#ccc, lightblue, orange, and #ccc—based on domain cutoffs at 0, 50, and 100. The SVG rendering uses d3-selection’s join() method to bind data generated by d3.range(-10, 110, 2). The result visually highlights the color transitions at the specified threshold boundaries.