Show array contents in a pop-up menu

[geuis]

I have data that is added to an array as the user inputs new data. What I would like to do is to make is so that the array data is displayed in a pop-up menu. When one of the selections in the menu is selected, it will then load notes about that input into a <textarea> box.
My main question is how can I display the contents of an array in a pop-up menu since the data is dynamic?

[geuis]

A normal drop-down menu. Sorry, over the years I've learned to alternately refer to them as pop-up menus or drop-down menus. Just a standard html menu. I want to store more and more data into an array and then be able to access it from a drop-down menu that updates itself with the new data. I was looking at another example you posted but I haven't quite gotten it down yet. I don't understand how to dynamically add more elements to a menu without it being hardcoded.