ant-design-blazor/components/core/JsInterop/modules/stateProvider.ts

import { eventCallback } from './dom/types'

//Singleton 
export class State {
  private static instance: State;

  //Stores references to dot net objects (components wrapped in DotNetObjectReference)
  objReferenceDict: { [key: string]: any } = {};

  //All object references must later be disposed by JS code or by .NET code.
  disposeObj(objReferenceName) {
    delete this.objReferenceDict[objReferenceName];
  }

  //Stores callback for events based on a key. Needed when
  //Event needs to be removed - the callback can be retrieved and
  //used to remove the event in question
  eventCallbackRegistry: { [key: string]: eventCallback} = {};
  
  oldBodyCacheStack = [];

  private constructor() { }

  static getInstance() {
    if (!this.instance) {
      this.instance = new State();      
    }
    return this.instance;
  }
}

export const state = State.getInstance();