Observer Pattern

hooks = {'EventA': [fn1, fn2]}

sub(type, fn):
    hooks[type].push(fn)

pub(type, data):
    hooks[type].each(fn => fn(data))

foo(thing):
    event = doStuff(thing)
    pub('EventA', event)

• events abstract actions from each other
• great for operations which are independent of each other
• bad for order of operations or ensuring that a thing actually happens (eg. potentially no subscribers but was desired)