Concatenate variables with Json keys.

Concatenate variables with Json keys.

Hi everyone,
I would like to ask for some help if you can.

I hope I'm explaining myself well. :-)

I have a json file with some data inside.
I load it via ajax.

I retrieve the key via this path.
  1. concatenate = JsonData.change_this.title
It works and returns the title to me.

Now what I'd like to do is change "change_this" to something dynamic.

What I tried is the following:
  1. new_change_this = "change_this_2";
    concatenate = JsonData.new_change_this.title
It gives me an error because I guess I am not able to concatenate this data correctly.

Is probably not an object but a string?
But I don't understand.

Can anyone give me a way forward?
Thank you all very much.
Have a great day.