Implement In-Memory Rate Limiter

Node.js

Technical Specification

Implement a basic in-memory rate limiter that allows only N requests per IP in a time window.

Input/Output Samples

Input:5 requests within 1 minute

Output:Allowed, then blocked

Optimal Logic Path

const buckets = new Map();

function isAllowed(ip, limit = 5, windowMs = 60000) {
  const now = Date.now();
  const list = (buckets.get(ip) || []).filter(
    (ts) => now - ts < windowMs
  );
  if (list.length >= limit) {
    buckets.set(ip, list);
    return false;
  }
  list.push(now);
  buckets.set(ip, list);
  return true;
}

module.exports = { isAllowed };

Architectural Deep-Dive

We track timestamps per IP and enforce a maximum count within a given timeframe.