A typed module which allows you to use tweens in Roblox with any easing function. It tries to behave as closely as possible to the behaviour of regular Tweens, including implementing the same methods and PlaybackStates.
import CustomTween from "@firere/custom-tween";
const gui = new Instance("ScreenGui");
const box = new Instance("Frame");
box.Size = UDim2.fromOffset(100, 100);
box.Parent = gui;
gui.Parent = Players.LocalPlayer.FindFirstChild("PlayerGui") as PlayerGui;
const tween = new CustomTween(box, { time: 5, easing: (x) => 1 - math.pow(1 - x, 5) }, { Position: UDim2.fromScale(1, 0) });
tween.Play();
task.wait(2.5);
tween.Cancel();