Rate limit tracker, adds a compounded penalty to the wait time with each offense over the limit

rate-limiter.js

import { action, computed, observable, reaction, when } from 'mobx';

export default class RateLimiter {
    @observable forgiveness;
    @observable limit;
    @observable offenses = 0;
    @observable queue = [];
    @observable wait;

    @computed get compoundedPenalty() {
        const i = (this.offenses - this.forgiveness) || 0;
        return (i * 1000);
    }

    @computed get overLimit() {
        return (this.queue.length >= this.limit);
    }

    constructor(limit = 3, wait = 4000, forgiveness = 1) {
        this.forgiveness = forgiveness;
        this.limit = limit;
        this.wait = wait;
        this.offenseHandler = reaction(() => this.overLimit, (overLimit) => {
            if (overLimit) this.offenses += 1;
        });
    }

    @action add = () => {
        if (this.overLimit) return false;
        let q = setTimeout(() => remove(), this.wait + this.compoundedPenalty);
        const remove = action(() => this.queue.remove(q));
        this.queue.push(q);
        when(() => this.queue.indexOf(q) === -1, () => {
            clearTimeout(q);
            q = null;
        });
        return remove;
    };

    @action destroy = () => {
        this.offenseHandler();
        this.queue.clear();
    };

}