Lightlimn Roblox Timer module remixed for TypeScript by FirstVertex

1_timer.ts

import { RunService } from "@rbxts/services";

export class Timer {
    constructor(private _duration: number, private _onComplete?: () => void, private _elapsed = 0, autoStart = true) {
        if (autoStart) {
            spawn(() => this.start());
        }
    }

    private _paused: boolean = true;
    private _startTime: number = 0;
    private _connection: RBXScriptConnection | undefined = undefined;

    start(duration = this._duration) {
        if (!this._paused || this._connection) {
            return;
        }
        this._duration = math.max(0, duration);
        this._startTime = os.clock() - this._elapsed;
        this._paused = false;

        this._connection = RunService.Heartbeat.Connect(() => {
            this._update()
        });
    }

    stop() {
        this._update();
        this._paused = true;
        if (this._connection) {
            this._connection.Disconnect();
            this._connection = undefined;
        }
    }

    getPercentComplete(): number {
        if (this._duration <= 0 || this._elapsed <= 0) {
            return 0;
        }
        if (this._elapsed >= this._duration) {
            return 1;
        }
        return this._elapsed / this._duration;
    }

    getRemainingTime(): number {
        return math.max(0, this._duration - this._elapsed);
    }

    private _update() {
        if (this._paused) {
            return;
        }
        const stamp = os.clock();
        const elapsed = stamp - this._startTime;
        if (elapsed >= this._duration) {
            this._paused = true;
            this._elapsed = this._duration;
            if (this._connection) {
                this._connection.Disconnect();
                this._connection = undefined;
            }
            if (this._onComplete !== undefined) {
                this._onComplete();
            }
        } else {
            this._elapsed = elapsed;
        }
    }
}

2_usage.ts

import { Timer } from "shared/timer";

export class MapStateTracker {
    constructor(delayInSeconds: number) { 
        this._timer = new Timer(delayInSeconds, () => this._moveToNextMap());
    }
    protected _timer: Timer;

    getCurrentMapPercentComplete(): number {
        return this._timer.getPercentComplete();
    }

    teardown() {
        if (this._timer) {
            this._timer.stop();
        }
    }

    protected _moveToNextMap() {
        // do work
    }
}

Remix from the original devforum post here
https://devforum.roblox.com/t/oop-timer-module/285360