My colorMap has the correct strings for filling the rectangles. Why no rectangles?
My codepen is https://codepen.io/richardvannie/pen/ByaLBvb
Can you provide a link to the challenge?
You’ll need to use sequential scales to create this colormap.
And here’s a good example in action, with docs:
https://d3-graph-gallery.com/graph/heatmap_style.html
Other docs but the above link is pretty good and thorough: