Setting a form input value using JS? Not being sent to backend

[notflip]

I'm trying to have JS fill in a form field value, and have that sent in my Form.

This is the JS code I'm using

document.querySelector('input[name=score]').value = 50

I can confirm that the JS is working, however the value is being lost when submitting the form.
Is there any other step that needs to be done to achieve this?

[edalzell]

Is score field in the Form blueprint?

[notflip]

Yes it is. I've tried setting it to "text" or to "hidden". Should it work out of the box when the form input is in the blueprint?