Rails: respond_to JSON and HTML

I have a controller "UserController" that should respond to normal and ajax requests to http://localhost:3000/user/3.

When it is a normal request, I want to render my view. When it is an AJAX request, I want to return JSON.

The correct approach seems to be a respond_to do |format| block. Writing the JSON is easy, but how can I get it to respond to the HTML and simply render the view as usual?

  def show
    @user = User.find(params[:id])
    respond_to do |format|
      format.html {
        render :show ????this seems unnecessary. Can it be eliminated??? 
      }
      format.json { 
        render json: @user
      }
    end
  end

As per my knowledge its not necessary to "render show" in format.html it will automatically look for a respective action view for ex : show.html.erb for html request and show,js,erb for JS request.

so this will work

respond_to do |format|

  format.html # show.html.erb
  format.json { render json: @user }

 end

also, you can check the request is ajax or not by checking request.xhr? it returns true if request is a ajax one.