This documentation is for ArcGIS REST JS 3.x which is no longer maintained. For the latest 4.x documentation see ArcGIS REST JS on the ArcGIS Developer website.
Version 3.4.3

@esri/arcgis-rest-types

Shared TypeScript types for @esri/arcgis-rest-js

npm install:

npm install @esri/arcgis-rest-types 

Module Import:

import {
  IUser, IItem
} from "@esri/arcgis-rest-types";

CDN:

<script src="https://unpkg.com/@esri/arcgis-rest-types@3.4.3/dist/umd/types.umd.min.js"></script>

CDN with SRI: