@thi.ng/server/interceptors/rate-limit.js

Minimal HTTP server with declarative routing, static file serving and freely extensible via pre/post interceptors

import { isNumber } from "@thi.ng/checks";
import { LeakyBucketMap } from "@thi.ng/leaky-bucket";
const rateLimiter = (opts) => new RateLimiter(opts);
class RateLimiter {
  buckets;
  capacity;
  clientID;
  constructor({
    id,
    maxBuckets,
    bucketCapacity,
    leakInterval
  }) {
    this.clientID = id ?? ((ctx) => ctx.req.socket.remoteAddress);
    this.capacity = isNumber(bucketCapacity) ? () => bucketCapacity : bucketCapacity;
    this.buckets = new LeakyBucketMap({ leakInterval, maxBuckets });
  }
  pre(ctx) {
    const id = this.clientID(ctx);
    if (!id) return true;
    const cap = !this.buckets.has(id) ? this.capacity(ctx, id) : void 0;
    if (!this.buckets.update(id, cap)) {
      ctx.res.rateLimit({}, `Try again later.`);
      return false;
    }
    return true;
  }
}
export {
  RateLimiter,
  rateLimiter
};