If I write, HA, it means I find what you said to be clever (this is an important distinction).
If I write, HAHA, it's sort of the wha-wha, not that funny.
If I write HAHAHAHA (or more HAHAHAs) then I have laughed heartily at you joke.
If I write LOL, this is a trick answer, it might mean I actually laughed outloud, or it might mean that I am being sarcastic and this is the shittiest attempt at a joke I have ever seen.
But for reals, this is a HA! (exclamation point) joke: