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){ document.getElementById(elementID).style.display = "inline"; } else { document.getElementById(elementID).style.display = "none"; } } public closeBootstrapModel(elementID: string): void{ document.getElementById(elementID).click(); } }