Godot For Loop: for, range() and Loops in GDScript

for repeats a block once for every item in something. The simplest form repeats a number of times:

extends Node

func _ready():
	for i in 3:
		print("Wave ", i)

Wave 0
Wave 1
Wave 2

for i in 3 is short for for i in range(3): i takes the values 0, 1 and 2. The end value is never included.

range(): Start, End and Step

range() takes up to three numbers: where to start, where to stop (not included) and how far to step:

extends Node

func _ready():
	print(range(5))
	print(range(2, 6))
	print(range(0, 20, 5))
	print(range(10, 0, -3))
	for i in range(5, 0, -1):
		print("Countdown: ", i)

[0, 1, 2, 3, 4]
[2, 3, 4, 5]
[0, 5, 10, 15]
[10, 7, 4, 1]
Countdown: 5
Countdown: 4
Countdown: 3
Countdown: 2
Countdown: 1

A negative step counts down. range() takes integers: a float argument is cut to a whole number, so range(0, 2, 0.5) fails with a zero step. For steps like 0.5, loop over integers and divide.

Looping Over an Array

Put the array after in and the loop variable holds one item each time:

extends Node

func _ready():
	var enemies := ["slime", "bat", "skeleton"]
	for enemy in enemies:
		print("Spawning a ", enemy)

Spawning a slime
Spawning a bat
Spawning a skeleton

You can type the loop variable: for enemy: String in enemies:.

Getting the Index

GDScript has no enumerate(). Loop over the indexes instead:

extends Node

func _ready():
	var podium := ["Ana", "Bo", "Chidi"]
	for i in podium.size():
		print(i + 1, ". ", podium[i])

1. Ana
2. Bo
3. Chidi

Looping Over a Dictionary

A for loop over a dictionary gives its keys. Read the value with the key:

extends Node

func _ready():
	var inventory := {"potion": 3, "arrow": 20, "key": 1}
	for item in inventory:
		print(item, ": ", inventory[item])
	for amount in inventory.values():
		print(amount)

potion: 3
arrow: 20
key: 1
3
20
1

Keys come out in the order they were added.

Looping Over a String and a Grid

A string gives its characters, one at a time. A grid of tiles is two loops, one inside the other:

extends Node

func _ready():
	for letter in "GO!":
		print(letter)
	for y in 2:
		for x in 3:
			print(Vector2i(x, y))

G
O
!
(0, 0)
(1, 0)
(2, 0)
(0, 1)
(1, 1)
(2, 1)

Nested loops like this one walk every cell of a tile grid, row by row.

break and continue

break leaves the loop. continue skips to the next item:

extends Node

func _ready():
	var rolls := [3, 0, 5, 6, 2]
	for roll in rolls:
		if roll == 0:
			continue  # skip a blank roll
		if roll == 6:
			print("Six! Stop rolling.")
			break
		print("Rolled ", roll)

Rolled 3
Rolled 5
Six! Stop rolling.

Removing Items While Looping

Removing from the array you are looping over shifts the items and the loop skips some. Loop backwards by index, or let filter() build a new array:

extends Node

func _ready():
	var hp_list := [10, 0, 5, 0, 8]
	for i in range(hp_list.size() - 1, -1, -1):
		if hp_list[i] == 0:
			hp_list.remove_at(i)
	print(hp_list)

	var scores := [4, 9, 2, 7]
	print(scores.filter(func(s): return s > 5))

[10, 5, 8]
[9, 7]

Loops in a Running Game

A for loop finishes inside one frame, so a loop of 100,000 steps freezes the game until it is done. For something that happens over time, such as a countdown, use _process(delta), a Timer or await instead of a loop.