import * as $ from "jquery"; export class CallbackManager { private static _instance: CallbackManager = new CallbackManager(); private constructor(){ if(CallbackManager._instance) { throw new Error("Error: Image object is already instantiated"); } else{ CallbackManager._instance = this; } } public static getInstance(): CallbackManager { return CallbackManager._instance; } public showElement(elementID: string, show: boolean): void { if(show){ $(elementID).css("display", "inline"); } else { $(elementID).css("display", "none"); } } }