progress and some refactoring

util/util.js

@@ -0,0 +1,31 @@
+
+// re-inventing the wheel:
+export function deepEqual(a, b) {
+  if (a === b) return true; // <- shallow equality and primitives
+  if (typeof a !== 'object' || typeof b !== 'object' || a === null || b === null) {
+    return false;
+  }
+  if (Array.isArray(a) && Array.isArray(b)) {
+    if (a.length !== b.length) return false;
+    for (let i = 0; i < a.length; i++) {
+      if (!deepEqual(a[i], b[i])) return false;
+    }
+    return true;
+  }
+  const keysA = Object.keys(a);
+  const keysB = Object.keys(b);
+  if (keysA.length !== keysB.length) return false;
+  for (let key of keysA) {
+    if (!keysB.includes(key) || !deepEqual(a[key], b[key])) {
+      return false;
+    }
+  }
+  return true;
+}
+
+// zip two arrays
+export function zip(a, b) {
+  return a.map((k, i) => [k, b[i]]);
+}
+
+