local UserInputService = game:GetService("UserInputService")
local localPlayer = game.Players.LocalPlayer
local character
local humanoid
local canDoubleJump = false
local hasDoubleJumped = false
local maxJumps = 5
local currentJump = 0
local oldPower
local TIME_BETWEEN_JUMPS = 0.2
local DOUBLE_JUMP_POWER_MULTIPLIER = 2
function onJumpRequest()
	if not character or not humanoid or not character:IsDescendantOf(workspace) or
		humanoid:GetState() == Enum.HumanoidStateType.Dead then
		return
	end
	if canDoubleJump and not hasDoubleJumped then
		if currentJump >= maxJumps then
			hasDoubleJumped = true
		end
		humanoid.JumpPower = oldPower * DOUBLE_JUMP_POWER_MULTIPLIER
		humanoid:ChangeState(Enum.HumanoidStateType.Jumping)
	end
end
local function characterAdded(newCharacter)
	character = newCharacter
	humanoid = newCharacter:WaitForChild("Humanoid")
	hasDoubleJumped = false
	canDoubleJump = false
	oldPower = humanoid.JumpPower

	humanoid.StateChanged:connect(function(old, new)
		if new == Enum.HumanoidStateType.Landed then
			canDoubleJump = false
			hasDoubleJumped = false
			currentJump = 0
			humanoid.JumpPower = oldPower
		elseif new == Enum.HumanoidStateType.Freefall then
			wait(TIME_BETWEEN_JUMPS)
			canDoubleJump = true
			currentJump = currentJump + 1
		end
	end)
end
if localPlayer.Character then
	characterAdded(localPlayer.Character)
end

localPlayer.CharacterAdded:connect(characterAdded)
UserInputService.JumpRequest:connect(onJumpRequest)
by

Lua online compiler

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Taking inputs (stdin)

OneCompiler's Lua online editor supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample Lua program which takes name as input and prints hello message with your name.

name = io.read("*a")
print ("Hello ", name)

About Lua

Lua is a light weight embeddable scripting language which is built on top of C. It is used in almost all kind of applications like games, web applications, mobile applications, image processing etc. It's a very powerful, fast, easy to learn, open-source scripting language.

Syntax help

Variables

  • By default all the variables declared are global variables
  • If the variables are explicitly mentioned as local then they are local variables.
  • Lua is a dynamically typed language and hence only the values will have types not the variables.

Examples

-- global variables
a = 10

-- local variables

local x = 30
Value TypeDescription
numberRepresents numbers
stringRepresents text
nilDifferentiates values whether it has data or not
booleanValue can be either true or false
functionRepresents a sub-routine
userdataRepresents arbitary C data
threadRepresents independent threads of execution.
tableCan hold any value except nil

Loops

1. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while(condition)
do
--code
end

2. Repeat-Until:

Repeat-Until is also used to iterate a set of statements based on a condition. It is very similar to Do-While, it is mostly used when you need to execute the statements atleast once.

repeat
   --code
until( condition )

3. For:

For loop is used to iterate a set of statements based on a condition.

for init,max/min value, increment
do
   --code
end

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increase re-usuability and modularity.

optional_function_scope function function_name( argument1, argument2, argument3........, argumentn)
--code
return params with comma seperated
end