"shoot a laser that moves to the mouse location using raycasting when E key is pressed"

-- local script 
local UserInputService = game:GetService("UserInputService")
local RunService = game:GetService("RunService")
local mouse = game.Players.LocalPlayer:GetMouse()

local function shootLaser()
	local origin = script.Parent.Position
	local direction = (mouse.Hit.p - origin).unit * 1000
	local ray = Ray.new(origin, direction)
	local hit, position = game.Workspace:FindPartOnRay(ray, script.Parent, false, true)

if hit then
		local laser = Instance.new("Part")
		laser.BrickColor = BrickColor.new("Bright red")
		laser.Anchored = true
		laser.CanCollide = false
		laser.FormFactor = Enum.FormFactor.Custom
		laser.Size = Vector3.new(0.2, 0.2, (position - origin).magnitude)
		laser.CFrame = CFrame.new((origin + position) / 2, position)
		laser.Parent = game.Workspace

game:GetService("Debris"):AddItem(laser, 0.1)
	end
end

UserInputService.InputBegan:Connect(function(input)
	if input.KeyCode == Enum.KeyCode.E then
		shootLaser()
	end
end)

RunService.RenderStepped:Connect(function()
	if UserInputService:IsKeyDown(Enum.KeyCode.E) then
		shootLaser()
	end
end)