Loops

Loops let you run a block of code multiple times without writing it out over and over. Luau has three kinds — each suited for different situations.

while

A while loop keeps running as long as its condition is true:

local count = 0

while count < 5 do
    print(count)
    count += 1
end

The condition is checked before each iteration. If it's false from the start, the loop body never runs at all.

repeat...until

repeat...until is the flip side of while. Instead of checking the condition at the start, it checks at the end — which means the body always runs at least once:

local count = 0

repeat
    print(count)
    count += 1
until count >= 5

The loop keeps repeating until the condition becomes true. It's useful when you always need to run the body at least once before deciding whether to continue — like prompting for user input and validating it afterward.

Numeric for

A numeric for loop runs a set number of times. You give it a start, a stop, and an optional step:

for i = 1, 5 do
    print(i) -- 1, 2, 3, 4, 5
end

By default the step is 1, but you can change it:

for i = 0, 10, 2 do
    print(i) -- 0, 2, 4, 6, 8, 10
end

You can also count backwards with a negative step:

for i = 5, 1, -1 do
    print(i) -- 5, 4, 3, 2, 1
end

Generalized Iteration

The generalized for loop is used to iterate over collections like tables. You'll learn about tables properly in a later chapter, but here's a quick look at what it looks like:

local fruits = {"apple", "banana", "cherry"}

for i, v in fruits do
    print(i, v)
end
-- 1  apple
-- 2  banana
-- 3  cherry

i is the index and v is the value at that index. This is one of the most common patterns you'll write in Luau, so it's worth getting familiar with the shape of it early even if tables aren't fully covered yet.

break

Any loop can be exited early with break:

for i = 1, 10 do
    if i == 5 then
        break
    end
    print(i) -- 1, 2, 3, 4
end

Once break is hit, Luau jumps out of the loop immediately and continues with whatever comes after it.