While looking at the js source from the checkout page I noticed an overload and override method which could be pretty neat for customization in some places. However these are not documented, but are documented in old 0.6 docs if I search for the methods.
Is it not advised to use these anymore? I could play with some extra showing/hiding of containers on the checkout page when the checkLogin method is executed for example.
I understand updates (fixes) on your end should not break the code on my end, so I probably won't be overriding core methods completely since it can be risky, but anyway.. you know what I mean