read parameters in javascript

I will send the parameter param = 5 to the chronoforms from the menu.
How can I read it on the page in javascript so that I can work with the parameter.
I tried
var param = jQuery ('# param'). val ();
but it doesn't read the value for me. I also tried to create a param field, it will be filled with parameters, but it will not be read in js.
I load Javascript right away with the page, it is not defined as a function.