javascript - Which data structure i should use to define and store users actions? -

my chrome extension uses drag , drop feature, works in way:

you grab object source page , drop target page, event corresponded set of predefined instructions (let's 3 async functions). after while drag again object , drop same area, popup message asks whether substitute or merge 2 objects (to commit operation need read done in past).

i wonder, data structure(perhaps stack), approach use in order set logical interpretation of instructions.