chore: split public and src

public/utils/functionUtils.js

@@ -0,0 +1,31 @@
+"use strict";
+// FMG helper functions
+
+// extracted d3 code to bypass version conflicts
+// https://github.com/d3/d3-array/blob/main/src/group.js
+function rollups(values, reduce, ...keys) {
+  return nest(values, Array.from, reduce, keys);
+}
+
+function nest(values, map, reduce, keys) {
+  return (function regroup(values, i) {
+    if (i >= keys.length) return reduce(values);
+    const groups = new Map();
+    const keyof = keys[i++];
+    let index = -1;
+    for (const value of values) {
+      const key = keyof(value, ++index, values);
+      const group = groups.get(key);
+      if (group) group.push(value);
+      else groups.set(key, [value]);
+    }
+    for (const [key, values] of groups) {
+      groups.set(key, regroup(values, i));
+    }
+    return map(groups);
+  })(values, 0);
+}
+
+function dist2([x1, y1], [x2, y2]) {
+  return (x1 - x2) ** 2 + (y1 - y2) ** 2;
+}