roblox-ts

Iteration

A guide on how to iterate in roblox-ts.

This page documents how to efficiently iterate in roblox-ts:

for..of Loops

Object.keys/Object.values/Object.entries/Array.entries all return arrays in roblox-ts, which allows us to use them in for..of loops:

const fibonacci = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144];

for (const [i, num] of fibonacci.entries()) {
	print(i, num);
}

In roblox-ts, our Array.reverse method returns a new array (unlike traditional TypeScript). You can also use these in for..of loops and expect optimized compiled code:

const fibonacci = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144];

for (const [i, num] of fibonacci.reverse().entries()) {
	print(i, num);
}

For objects, you can iterate through them using Object.entries (Object.keys/Object.values work similarly):

const obj = { a: 1, b: 2, c: 3 } as const;

for (const [i, v] of Object.entries(obj)) {
	print(i, v);
}

The following objects can all be directly iterated over via the for..of loop:

for (const x of [0, 1]);
for (const x of "Hello, world");
for (const x of new Set(["a", "b", "c", "d", "e"]));
for (const [i, x] of new Map([["a", 1], ["b", 2], ["c", 3]]));
for (const [x] of "I am so cool".gmatch("%S+"));
for (const x of {
	*[Symbol.iterator]() {
		yield 1;
	},
});

Since Object.keys/Object.values/Object.entries/Array.entries/Array.reverse are optimized to pairs and numeric for loops, these optimized loops may be affected by writing to the object which is being iterated through. It is considered bad practice to write to an object while iterating through it. If the intention is to cache Object.entries and then iterate through it, simply put it in a variable above the for..of loop instead of having it in-line. {:.warn}