A health gui problem!?

Problems

• WaitForChild

  • The lack of the WaitForChild method in this code is just asking for an error. You cannot confirm that any object you're trying to access within the script will be loaded and ready to use at run time, therefore WaitForChild (or at very least, FindFirstChild) should be implimented.

• Loops

  • Loops are wonderful. However in this case, they're not needed. There's an event specifically for when the Humanoid's health is changed called "HealthChanged", deprecating the need to constantly check the health over and over.

• Local script

  • This code should be inside a local script, since it's dealing with the individual player and not replicating changes to the server. Whenever you're dealing with user input, or just animating or configuring GUIs, you should always be doing it client-sided.

• LocalPlayer

  • Because this should be in a local script, you should be utilizing the LocalPlayer feature which is a member of the Players service (exclusively for local scripts). This will return the player the script is a descendant of, instead of needing to write out it's full hierarchy.

• Character

  • I'm seperating this from my WaitForChild explanation, since you can't use WaitForChild for the player's character. Instead, you should be using the wait method of the CharacterAdded event, combined with an or condition that chooses it's alternative if the character does not exist. Here's an example:

    -- Gets, or waits and returns the character.
    local char = player.Character or player.CharacterAdded:wait()
  

Solution

So applying all I went over above, we should have something like this:

-- Getting the local player
local player = game:GetService("Players").LocalPlayer

-- Gets, or waits and returns the character.
local char = player.Character or player.CharacterAdded:wait()

-- Using WaitForChild to load the Humanoid.
local human = char:WaitForChild("Humanoid")

-- Get the health bar
local healthBar = script.Parent:WaitForChild("Healthbar")

-- Get the text label
local healthNum = script.Parent:WaitForChild("HealthNum")

-- Now connecting the event called "HealthChanged" which fires obviously, when the humanoid's health is changed.
human.HealthChanged:connect(function(health)
	local max = human.MaxHealth

	-- Update the info with the given stats
	healthNum.Text = math.floor(health).."/"..max
	healthBar.Size = UDim2.new(health/max,0,1,0)

end) -- End the event.

Hope that helped, if you have any questions let me know.