warning on dublicate ids

src/Container.ts

@@ -1,9 +1,9 @@
 import { Util, Collection } from './Util';
 import { Factory, Validators } from './Factory';
-import { Node } from './Node';
-import { getGlobalKonva, ids, names } from './Global';
+import { Node, ids } from './Node';
+import { getGlobalKonva, names } from './Global';
 
-import { GetSet, Vector2d, IRect } from './types';
+import { GetSet, IRect } from './types';
 
 /**
  * Container constructor.  Containers are used to contain nodes or other containers

src/Global.ts

@@ -15,8 +15,6 @@ var PI_OVER_180 = Math.PI / 180;
  */
 export const version = '@@version';
 
-// private
-export const ids = {};
 export const names = {};
 export const shapes = {};
 
@@ -66,32 +64,6 @@ export const isDragReady = function() {
   }
   return false;
 };
-export const _addId = function(node: any, id) {
-  if (!id) {
-    return;
-  }
-  // do we need this warning?
-  // if (ids[id]) {
-  //   console.warn(
-  //     'Duplicate id "' +
-  //       id +
-  //       '". Please don not use same id several times. It may break find() method look up.'
-  //   );
-  // }
-  ids[id] = node;
-};
-
-export const _removeId = function(id: string, node: any) {
-  // node has no id
-  if (!id) {
-    return;
-  }
-  // another node is registered (possible for duplicate ids)
-  if (ids[id] !== node) {
-    return;
-  }
-  delete ids[id];
-};
 
 export const _addName = function(node: any, name) {
   if (name) {

src/Node.ts

@@ -1,16 +1,39 @@
 import { Util, Collection, Transform, RectConf, Point } from './Util';
 import { Factory, Validators } from './Factory';
 import { SceneCanvas, HitCanvas } from './Canvas';
-import {
-  _removeId,
-  _removeName,
-  _addId,
-  _addName,
-  getGlobalKonva
-} from './Global';
+import { _removeName, _addName, getGlobalKonva } from './Global';
 import { Container } from './Container';
 import { GetSet, Vector2d } from './types';
 
+export const ids = {};
+
+const ID_WARNING = `Duplicate id "{id}".
+Please do not use same id several times, it will break find() method look up.
+If you have duplicates it is better to use "name" property instead.
+`;
+
+const _addId = function(node: Node, id) {
+  if (!id) {
+    return;
+  }
+  if (ids[id]) {
+    Util.warn(ID_WARNING.replace('{id}', id));
+  }
+  ids[id] = node;
+};
+
+export const _removeId = function(id: string, node: any) {
+  // node has no id
+  if (!id) {
+    return;
+  }
+  // another node is registered (possible for duplicate ids)
+  if (ids[id] !== node) {
+    return;
+  }
+  delete ids[id];
+};
+
 export type Filter = (this: Node, imageData: ImageData) => void;
 
 type globalCompositeOperationType =

src/internals.ts

@@ -1,7 +1,7 @@
 export * from './Global';
 
 export { Collection, Util } from './Util';
-export { Node } from './Node';
+export { Node, ids } from './Node';
 export { Container } from './Container';
 
 export { Stage, stages } from './Stage';