refactor(es modules): migrate colorUtils

src/utils/colorUtils.ts

@@ -0,0 +1,40 @@
+const d3 = window.d3;
+
+const c12 = [
+  "#dababf",
+  "#fb8072",
+  "#80b1d3",
+  "#fdb462",
+  "#b3de69",
+  "#fccde5",
+  "#c6b9c1",
+  "#bc80bd",
+  "#ccebc5",
+  "#ffed6f",
+  "#8dd3c7",
+  "#eb8de7"
+];
+
+export function getColors(number: number) {
+  const cRB = d3.scaleSequential(d3.interpolateRainbow);
+  const colors = d3.shuffle(
+    d3
+      .range(number)
+      .map((index: number) => (index < 12 ? c12[index] : d3.color(cRB((index - 12) / (number - 12))).hex()))
+  );
+  return colors;
+}
+
+export function getRandomColor() {
+  return d3.color(d3.scaleSequential(d3.interpolateRainbow)(Math.random())).hex();
+}
+
+// mix a color with a random color
+export function getMixedColor(hexColor: string, mixation = 0.2, bright = 0.3) {
+  // if provided color is not hex (e.g. harching), generate random one
+  const color1 = hexColor && hexColor[0] === "#" ? hexColor : getRandomColor();
+  const color2 = getRandomColor();
+  const mixedColor = d3.interpolate(color1, color2)(mixation);
+
+  return d3.color(mixedColor).brighter(bright).hex();
+}