Please find screenshot: Initially I find min function is available in Math Object. I have updated "min" property with function. This action replaced the existing code.
For more clarity I have deleted the property from "min". Here deletion should remove the extended behavior not the core one. But it is removing core property why?
In short, when you delete a function that you've modified, you will be deleting it entirely, not reverting it back to some sort of original state. You basically overwrote the original, and so there's no way of getting it back (except by deleting the code that overwrites it!).