Is this what you mean?
There is a system, I don't know about the other question.
Though to be honest I only logged into and replied to this because I want to say how much I hate you, and people that think "WoW" created everything.
Jump was created WAY before WoW, say "Jump like in Half life?" please and thanks.
look, i know that not everyone plays DotA, but if you have a look at the character Priestess of the Moon, one of her skills "leaps" forwards, adding special buffs and allowing her to cross unpassable terrain (up/down cliffs, jumping over/on enemy units) I will be basing my help on that. if you only want the unit to jump straight up, then i cannot help you.
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First of all, you will want to make a trigger that moves the unit forwards, for example,
1. pause unit
2. move unit(instantly) a
short distance every 0.03 seconds (that way it will look like the unit is moving) the way to do this would be to move to move unit in a diection = "unit facing angle" don't forget that string!
3. i don't know how to do the up/down effect, so i am totally guessing here - raise/lower unit height (thismay be in something like set custom value, or you may have to use JASS (I can't, so if you can, you're doing better than me!)
That's as much as i can give! hope it helps!
OH! and to assign spacebar? i'm not exactly sure, but if you go to abilities, and edit you're jump ability, you should see something like "hotkey" near the bottom (if the skill has more than one level, then it
may be above Data, but i'm not sure)