MinuteScheduler Class: Similar to setInterval, but aligned to the minute or a multiple of it, while also accounting for drift.

MinuteScheduler.ts

const roundToNextDivisible = (num: number, interval: number) => {
    return Math.ceil(num / interval) * interval;
};


/**
 * Similar to setInterval, but aligned to the minute or a multiple of it, while also accounting for drift.
 */
export default class MinuteScheduler {
    public tsLast = Date.now();
    constructor(
        private readonly callback: () => void,
        private readonly intervalMins = 1,
        alignInitial = true,
    ) {
        if (this.intervalMins < 1) {
            throw new Error('intervalMins must be at least 1');
        }
        if (this.intervalMins > 59) {
            throw new Error('intervalMins must be at most 59');
        }
        if (this.intervalMins % 1 !== 0) {
            throw new Error('intervalMins must be an integer');
        }

        if (intervalMins !== 1 && alignInitial) {
            this.alignInitial();
        } else {
            this.scheduleNext();
        }
    }


    /**
     * Awaits until the minutes are divisible by this.intervalMins before starting the loop.
     */
    private async alignInitial() {
        //If it's already aligned, start the loop
        const now = new Date();
        if (now.getMinutes() % this.intervalMins === 0) {
            this.run();
            return;
        }

        //Find the next minute divisible and wait for it
        const nextRun = new Date();
        const currMinute = nextRun.getMinutes();
        const nextMinute = roundToNextDivisible(currMinute, this.intervalMins);
        const nextRunTs = nextRun.setMinutes(nextMinute, 0, 0);
        const msDelay = nextRunTs - Date.now();

        //Schedule first run
        setTimeout(() => this.run(), msDelay);
    }


    /**
     * Schedules the next run.
     */
    private scheduleNext() {
        const now = new Date();
        const nextTs = now.setMinutes(now.getMinutes() + this.intervalMins, 0, 0);
        const delay = nextTs - Date.now();
        setTimeout(() => this.run(), delay);
    }


    /**
     * Runs the callback and schedules the next run.
     */
    private run() {
        this.tsLast = Date.now();
        this.callback();
        this.scheduleNext();
    }
}