Conditionals and Loops

Written: 2026-10-14

Learning objectives

• You branch with if, elseif, and else.
• You repeat with while, repeat-until, and numeric for.
• You stop or skip with break and continue as the last statement in their block.
• You pick the right loop for each job.
• You keep every loop safe with task.wait.

Prerequisites

• Read First Script. You can run a Script and read output.
• Read Variables and Values. You create and print variables.
• Read Operators and Logic. You compare values and combine booleans.

Choose a path with if

control structures steer your code. An if statement asks a yes-or-no question and runs code only on yes. elseif asks a second question when the first answer was no. else catches everything left over. Luau reads the chain top to bottom and runs only the first branch whose condition is true.

Run this: put it in a Script in ServerScriptService and press Play.

--!strict
local level = 7
if level >= 10 then
	print("Master")
elseif level >= 5 then
	print("Skilled")
else
	print("Beginner")
end

Skilled

Walkthrough:

1. Line 1 turns on strict mode.
2. Line 2 stores 7 in level.
3. Line 3 asks "is 7 >= 10?" The answer is false, so Luau skips line 4.
4. Line 5 asks "is 7 >= 5?" The answer is true, so Luau runs line 6.
5. Line 6 prints Skilled.
6. Lines 7 to 9 close the chain. The else branch is skipped because a branch already ran.

Every condition here is a comparison that returns a boolean. You built those in Operators and Logic. Remember that only nil and false count as false. The number 0 and the empty string count as true.

Repeat while something is true

A while loop repeats its body for as long as its condition stays true. It checks the condition first, so the body may run zero times. This loop fits jobs where you do not know the count up front, like counting down a timer.

Run this: put it in a Script in ServerScriptService and press Play.

--!strict
local countdown = 3
while countdown > 0 do
	print(countdown)
	countdown = countdown - 1
	task.wait(0.1)
end
print("Go!")

3
2
1
Go!

Walkthrough:

1. Line 1 turns on strict mode.
2. Line 2 stores 3 in countdown.
3. Line 3 checks countdown > 0. While true, the body runs.
4. Line 4 prints the current count.
5. Line 5 subtracts one so the loop moves toward its end.
6. Line 6 pauses briefly so the loop yields. You will learn why below.
7. Line 8 prints Go! after the loop finishes.

Line 5 subtracts one so the loop moves toward its end. Something inside the body must push the condition toward false. Without that change, the loop never ends.

Repeat at least once with repeat-until

A repeat-until loop runs its body first and checks the condition after. The body always runs at least once. The loop stops when the condition turns true. Luau also extends visibility here: a local variable you declare inside the body stays visible in the until condition.

Run this: put it in a Script in ServerScriptService and press Play.

--!strict
local total = 0
repeat
	total = total + 1
	local doubled = total * 2
	print(doubled)
	task.wait(0.1)
until doubled >= 6

2
4
6

Walkthrough:

1. Line 1 turns on strict mode.
2. Line 2 stores 0 in total.
3. Line 3 starts the loop. There is no condition here because the check comes last.
4. Line 4 adds one to total.
5. Line 5 creates doubled from the new total.
6. Line 6 prints it.
7. Line 7 pauses briefly so the loop yields.
8. Line 8 checks doubled >= 6. Notice doubled was declared inside the loop, yet the condition can still see it. The loop repeats until this turns true.

Use repeat-until when the first run must happen no matter what, like showing a menu at least once before checking whether the player quit.

Count exactly with numeric for

A numeric for loop counts from a start to an end in steps you choose. You get a counter variable that updates itself each round. This loop fits jobs where you know the count up front, like dealing five cards.

Run this: put it in a Script in ServerScriptService and press Play.

--!strict
for deal = 1, 5 do
	print(deal)
end

1
2
3
4
5

Walkthrough:

1. Line 1 turns on strict mode.
2. Line 2 starts deal at 1 and repeats the body until deal passes 5, adding 1 each round.
3. Line 3 prints the current counter.
4. Line 4 ends the loop body.

The step defaults to 1. Add a third number to change it. A step of 2 counts odd numbers. A negative step counts down. The end value is included when the counter lands on it.

Run this: put it in a Script in ServerScriptService and press Play.

--!strict
for seat = 1, 5, 2 do
	print(seat)
end
for rocket = 3, 1, -1 do
	print(rocket)
end

1
3
5
3
2
1

Walkthrough:

1. Line 1 turns on strict mode.
2. Line 2 counts seat from 1 to 5 in steps of 2.
3. Line 3 prints 1, then 3, then 5.
4. Line 5 counts rocket from 3 down to 1 in steps of -1.
5. Line 6 prints 3, then 2, then 1.

Never assign to the counter inside the body. Luau owns the counter and resets it each round. Your assignment would be overwritten and only confuse you.

Stop early with break and skip with continue

break ends a loop immediately. continue skips the rest of the current round and starts the next one. Both must sit as the last statement in their block. In practice that means you put each one alone inside an if branch, as the final line before end.

Run this: put it in a Script in ServerScriptService and press Play.

--!strict
for ticket = 1, 10 do
	if ticket > 3 then
		break
	end
	print(ticket)
end

1
2
3

Walkthrough:

1. Line 1 turns on strict mode.
2. Line 2 counts ticket from 1 to 10.
3. Line 3 checks whether the counter passed 3.
4. Line 4 runs break as the last statement of the if block. The loop ends at once.
5. Line 6 prints the counter, but only for rounds that did not break.

Run this: put it in a Script in ServerScriptService and press Play.

--!strict
for ticket = 1, 5 do
	if ticket % 2 == 0 then
		continue
	end
	print(ticket)
end

1
3
5

Walkthrough:

1. Line 1 turns on strict mode.
2. Line 2 counts ticket from 1 to 5.
3. Line 3 checks for even numbers with the remainder operator.
4. Line 4 runs continue as the last statement of the if block. The print below is skipped for this round.
5. Line 6 prints only the odd tickets: 1, 3, 5.

If strict mode complains about your break or continue, look at what follows it in the same block. Move it to the end so nothing comes after it except end.

Pick the right tool

Use if when code runs zero or one times depending on a condition. For repeats, while fits an unknown number of times that may never run, repeat-until fits a body that must run at least once, and numeric for fits a known range. Use break when you found what you sought, and continue when some rounds deserve skipping.

Keep loops safe with task.wait

A loop with no pause can spin thousands of times per second and freeze your game. The call task.wait(0.1) pauses the loop for about a tenth of a second and lets the rest of the game run. Put one inside every loop that might run long, especially while true loops. This pause keeps the game responsive. You use the call here as a safety pause; Task and Async teaches the full scheduling story later.

Run this: put it in a Script in ServerScriptService and press Play, then stop the game after a few seconds.

--!strict
local ticks = 0
while true do
	ticks = ticks + 1
	print(ticks)
	task.wait(0.5)
	if ticks >= 3 then
		break
	end
end

1
2
3

Walkthrough:

1. Line 1 turns on strict mode.
2. Line 2 stores 0 in ticks.
3. Line 3 starts an endless loop. The condition true never turns false by itself.
4. Line 4 adds one to ticks.
5. Line 5 prints the count.
6. Line 6 pauses half a second. Delete this line and the loop would spam with no pause.
7. Lines 7 to 9 break out once three rounds have printed. This break is your exit plan.

Every endless loop needs two things: a task.wait inside, and a break condition you can reach. Check both before you press Play.

Common mistakes

Writing = in a condition.

Run this to see it fail: put it in a Script in ServerScriptService and press Play.

--!strict
local level = 5
if level = 5 then
	print("ready")
end

Red syntax error on line 3: the script does not run until you compare with ==.

Conditions compare with ==. Fix it with two equals signs. Run the fix the same way.

--!strict
local level = 5
if level == 5 then
	print("ready")
end

ready

Forgetting to move a while loop toward its end.

Run this to see it fail: put it in a Script in ServerScriptService and press Play, then stop the game after a few seconds.

--!strict
local countdown = 3
while countdown > 0 do
	print(countdown)
	task.wait(0.1)
end

3
3
3
... repeats 3 forever, because countdown never changes. Stop the game.

This loops forever because countdown never changes. Fix it by updating the variable inside the body. Run the fix the same way.

--!strict
local countdown = 3
while countdown > 0 do
	print(countdown)
	countdown = countdown - 1
	task.wait(0.1)
end

3
2
1

Putting code after break in the same block.

Run this to see it fail: put it in a Script in ServerScriptService and press Play.

--!strict
for ticket = 1, 10 do
	if ticket > 3 then
		break
		print(ticket)
	end
end

Red error on line 5: break must be the last statement in its block, so the script does not run.

Strict mode rejects code after break in one block. Fix it by making break the last statement. Run the fix the same way.

--!strict
for ticket = 1, 10 do
	if ticket > 3 then
		break
	end
	print(ticket)
end

1
2
3

Looping with no pause.

Run this to see it fail: put it in a Script in ServerScriptService and press Play, then stop the game quickly.

--!strict
while true do
	print("spin")
end

spin
spin
spin
... spams with no pause and freezes your game. Stop the game.

This freezes your game because nothing ever yields. Fix it with a wait and an exit. Run the fix the same way.

--!strict
local spins = 0
while true do
	spins = spins + 1
	print("spin")
	task.wait(0.5)
	if spins >= 2 then
		break
	end
end

spin
spin

Exercises

Run every solution below in a Script in ServerScriptService and press Play. Try each exercise yourself before you open its solution.

1. Store a health value of 60. Print "Healthy" when it is at least 50, "Hurt" when it is at least 20, and "Down" otherwise.

Solution 1

--!strict
local health = 60
if health >= 50 then
	print("Healthy")
elseif health >= 20 then
	print("Hurt")
else
	print("Down")
end

Healthy

2. Use a while loop to print 5 down to 1, then print "Go!". Include task.wait(0.1) in the loop.

Solution 2

--!strict
local countdown = 5
while countdown > 0 do
	print(countdown)
	countdown = countdown - 1
	task.wait(0.1)
end
print("Go!")

5
4
3
2
1
Go!

3. Use a numeric for loop to print the even numbers from 2 to 10. Hint: step by 2 from 2.

Solution 3

--!strict
for even = 2, 10, 2 do
	print(even)
end

2
4
6
8
10

4. Print tickets 1 to 8, but skip multiples of 3 with continue and stop completely after printing 7 with break. Include task.wait(0.1) in the loop.

Solution 4

--!strict
for ticket = 1, 8 do
	if ticket % 3 == 0 then
		continue
	end
	print(ticket)
	task.wait(0.1)
	if ticket >= 7 then
		break
	end
end

1
2
4
5
7

Line 3 skips 3 and 6. Line 7 prints the rest. Lines 9 to 11 stop the loop after 7, so 8 never prints.

Summary

You branched with if, elseif, and else. You repeated with while for unknown counts, repeat-until for run-at-least-once, and numeric for for exact counts. You stopped loops with break and skipped rounds with continue, each as the last statement in its block. You kept loops safe with task.wait and a reachable exit.

Next: Functions and Scope.