callbacks.ts

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");
        }
    }
}