Unity editor script to bulk rename the children of a given gameobject

bulkRename.cs

 using UnityEngine;
 using UnityEditor;
 
 public class RenameChildren : EditorWindow {
     private static readonly Vector2Int size = new Vector2Int(250, 100);
     private string childrenPrefix;
     private int startIndex = 0;

     [MenuItem("GameObject/Rename children")] public static void ShowWindow() {
         EditorWindow window = GetWindow<RenameChildren>();
         window.minSize = size;
         window.maxSize = size;
     }

     private void OnGUI() {
         childrenPrefix = EditorGUILayout.TextField("Children prefix", childrenPrefix);
         if (GUILayout.Button("Rename children")) {
             GameObject[] selectedObjects = Selection.gameObjects;
             for (int objectI = 0; objectI < selectedObjects.Length; objectI++) {
                 Transform selectedObjectT = selectedObjects[objectI].transform;
                 for (int childI = 0, i = startIndex; childI < selectedObjectT.childCount; childI++) selectedObjectT.GetChild(childI).name = $"{childrenPrefix}{selectedObjectT.GetChild(childI).name}";
             }
         }
     }
 }