Danika's lightwhip doesn't have an actual whip cord. When it's deactivated, you just see a lightsaber hilt.
There are lightwhips that have physical cords, like Lumiya's, but that was a rare version.
Besides, who's to say if a slaver's shock whip exists, some Jedi didn't think, " We could use something like that ourselves for non-lethal combat. " or something?
As well, look at the picture of the shock whip here. It has a cord.
http://starwars.wikia.com/wiki/Shock_whipI would imagine that a whip can be both with and without a cord. Both versions have strengths and weaknesses, so it kinda makes sense.