Make nodes editable: norms, goals and keyword triggers

src/utils/duplicateIndices.ts

@@ -0,0 +1,19 @@
+/**
+ * Find the indices of all elements that occur more than once.
+ *
+ * @param array The array to search for duplicates.
+ * @returns An array of indices where an element occurs more than once, in no particular order.
+ */
+export default function duplicateIndices<T>(array: T[]): number[] {
+  const positions = new Map<T, number[]>();
+
+  array.forEach((value, i) => {
+    if (!positions.has(value)) positions.set(value, []);
+    positions.get(value)!.push(i);
+  });
+
+  // flatten all index lists with more than one element
+  return Array.from(positions.values())
+    .filter(idxs => idxs.length > 1)
+    .flat();
+}