JS function to enable/disable button, based on state change of toggle (switch)

I am looking for a JS function that detects when a toggle state is changed (sometimes the toggle will be checked on load, sometimes the toggle will be unchecked on load)... I need the JS function to detect when the state is changed (not just if it is checked or if it is unchecked). This is so that the disabled "Apply" button under the toggle only becomes enabled if the toggle state is changed from what it was on load.

And, as explained in the Word doc attached, if the toggle is clicked back to its original state... the button should go back to being disabled, as there is no need to apply anything.

There are examples and screen captures in the attached Word doc.