how do i run an animation in a while loop?

so im trying to run an animation in a while loop but the animation just stops working and it doesnt work right

idk whats wrong but here is my code

local slash1 = Instance.new("Animation")
slash1.AnimationId = "http://www.roblox.com/Asset?ID=166956234"
local swordslash1 = game.Players.LocalPlayer.Character.Humanoid:LoadAnimation(slash1)

function swordslash()
	print'animating'
	animating = true
	swordslash1:Play()
	wait(3)
	animating = false
end

animating = false
function update() 
	if script.Parent.Equipped.Value == "IronSword" then
		
		sword.BrickColor = BrickColor.new("Dark stone grey")
		mesh.MeshId = "rbxasset://fonts/sword.mesh"
		mesh.TextureId = ""
		
		if script.Parent.Button1DownValue.Value == true then
			if animating == false then
				swordslash()
			end
		end
	end
end

while wait() do
	update()
end

Is this in a LocalScript? Animations for player characters must be played from a Local Script to work. (http://wiki.roblox.com/index.php?title=Animations#Using_Animation_in_Games)

--MightyWanderer