such a situation
, there are 4 blocks, 2 buttons.. each button for 2 units.
By default, one button class "active" and block 2 active (displayed).
Need, something hovering - changing class clicking remained and changed blocks (if you pressed the wrong button that is already active).
Ie page loaded = pressed the first button (there is class), removed the first 2 blocks. Lead the mouse class the change. Clicked on another button = pressed now she (her class) and implemented 2 other block.
Even hovering can not think of how to implement, I thought about e.target, but no)
UPD: well, pressing with the default.. implemented Guidance is not given)