Collecting Values from Slider Bar

Hello, I have a question about the example from

How do I collect the value of the slider that I locate?
For example, if I move the slider to somewhere around 50 (out of 100), how do I collect that value (i.e., 50) using something like “submit” function in the post method? Or is there any way to collect the slider data if I am going to use it for an experiment?

I would really appreciate if anyone could answer my question.
Many thanks!