Persist items identity

package.json

@@ -1,6 +1,6 @@
 {
   "name": "vscroll",
-  "version": "1.8.2",
+  "version": "1.8.3",
   "description": "Virtual scroll engine",
   "main": "dist/bundles/vscroll.umd.js",
   "module": "dist/bundles/vscroll.esm5.js",

src/classes/item.ts

@@ -3,6 +3,7 @@ import { Direction } from '../inputs/index';
 import { Item as _Item, ItemAdapter } from '../interfaces/index';
 
 export class Item<Data = unknown> implements _Item<Data> {
+  private static nextUid = 1;
   nodeId: string;
   routines: Routines;
   preSize: number; // estimated size
@@ -14,6 +15,13 @@ export class Item<Data = unknown> implements _Item<Data> {
 
   private container: ItemAdapter<Data>;
 
+  get uid(): number {
+    return this.container.uid;
+  }
+  set uid(value: number) {
+    this.container.uid = value;
+  }
+
   get $index(): number {
     return this.container.$index;
   }
@@ -37,6 +45,7 @@ export class Item<Data = unknown> implements _Item<Data> {
 
   constructor($index: number, data: Data, routines: Routines) {
     this.container = {
+      uid: Item.nextUid++,
       $index,
       data
     };

src/interfaces/adapter.ts

@@ -42,6 +42,7 @@ export interface IAdapterProp {
 }
 
 export interface ItemAdapter<Data = unknown> {
+  uid: number;
   $index: number;
   data: Data;
   element?: HTMLElement;

src/interfaces/item.ts

@@ -1,6 +1,7 @@
 import { ItemAdapter } from './adapter';
 
 export interface Item<Data = unknown> {
+  uid: number;
   $index: number;
   element: HTMLElement;
   data: Data;

src/version.ts

@@ -1,4 +1,4 @@
 export default {
   name: 'vscroll',
-  version: '1.8.2'
+  version: '1.8.3'
 };

tests/package.json

@@ -1,6 +1,6 @@
 {
   "name": "vscroll-tests",
-  "version": "1.8.2",
+  "version": "1.8.3",
   "private": true,
   "description": "Test suite for vscroll",
   "type": "module",