Ability to set ID on form elements

I would like the ability to manually set the form ID for form elements. I need this ability because we create custom JavaScript to modify the functionality of some forms. I can work with the auto-assigned form ID, but if we make a change to the form and add/remove form fields above an affected field, the field ID changes.

When that happens I have to find the new field ID and change my JavaScript. It is tedious. If I could set the field ID, then I wouldn't have to worry about that.

Note that the field ID should be optional and default to whatever is currently generated if blank.