Why do people use pairs() or ipairs() when doing :GetChildren()?

[notsad2 (nots7d)]

title is very self explanatory,

:GetChildren() returns an array, not a dictionary, and pairs() with ipairs() are meant to be used with dictionaries

here’s an example codeblock:

-- loop through all the enemies
	for _, enemy in ipairs(enemies) do -- why use ipairs when it's an array?
		-- get required parts of the enemy
		local enemyRootPart:BasePart = enemy:FindFirstChild("HumanoidRootPart")
		local enemyHumanoid: Humanoid = enemy:FindFirstChild("Humanoid")
		
		-- if the enemy is unable to attack in any form
		-- like it's dead or something, skip the iteration
		if not CanEnemyBeUsed(enemy) then continue end
		
		-- get stats of the enemy
		local enemyMaxHealth = enemyStats[enemy.Name].health
		local enemySiphonOnKill = enemyStats[enemy.Name].siphon
		
		local enemyDeathEvent = enemyStats[enemy.Name].deathEvent
		local enemyBehavior = enemyStats[enemy.Name].behavior
		local enemyAttackTimes = GetAttackTimes(enemy)
		
		
	end

[Ziffixture (Ziffix)]

The Lua(u) table is a hybrid data structure. It’s internally comprised of an array component and a hash-map (dictionary) component. pairs and ipairs are iterator factories designed to produce specialized iterators for the traversal of this data structure. They do not do the same thing.

• An ipairs iterator will traverse by ascending indices, which typically results in the elements of the array component from left → right. The iterator will cease function upon discovering a nil element

• pairs uses the next function, which is designed to cover both the array and dictionary components. Dictionaries cannot naturally preserve insertion order, so a pairs iterator traverses in no defined order. The iterator will cease iteration upon reaching the end of the table

TL;DR: ipairs is optimized for traversal of the array component, while pairs is designed to cover the entire table.

With the introduction of generalized iteration, both factories are no longer required

[RoloTheDevBunny (Rolo)]

Originally it was necessary to loop through a list of items, now it isn’t. Ipairs runs numerically for lists, so it can be beneficial at times. It doesn’t work for objects with non-numeric key value pairs, and it also stops at the first nil value(in standard lua). I would recommend playing around in Roblox so you fully understand the differences.