refactor: extract utility to merge two arrays

packages/utils/index.ts

@@ -61,7 +61,7 @@ export { customFieldLabelToKey, customKeyFromLabel } from './src/customField-uti
 export { deepmerge } from './src/externals/deepmerge.js';
 
 // array utils
-export { deleteAtIndex, insertAtIndex, reorderArray } from './src/common/arrayUtils.js';
+export { deleteAtIndex, insertAtIndex, mergeAtIndex, reorderArray } from './src/common/arrayUtils.js';
 // object utils
 export { getPropertyFromPath, isObjectEmpty } from './src/common/objectUtils.js';
 

packages/utils/src/common/arrayUtils.ts

@@ -25,6 +25,24 @@ export function insertAtIndex<T>(index: number, item: T, array: T[]): T[] {
   return modifiedArray;
 }
 
+/**
+ * Inserts an array into another one of the same type at a given index
+ */
+export function mergeAtIndex<T>(index: number, newArray: T[], currentArray: T[]): T[] {
+  // Insert at beginning
+  if (index === 0) {
+    return [...newArray, ...currentArray];
+  }
+
+  // insert at end
+  else if (index >= currentArray.length) {
+    return [...currentArray, ...newArray];
+  }
+
+  // insert in the middle
+  return currentArray.toSpliced(index, 0, ...newArray);
+}
+
 /**
  * Deletes array element at a given index
  * @param index