Lesson 24 — Sliding-window rate limiter

Count only recent calls

A fixed window limiter ("100 per minute, counter resets at :00") lets a client do 100 calls at 0:59 and 100 more at 1:00. A sliding window keeps the timestamps of recent calls and, on each request, forgets those older than the window. If fewer than max remain, the call is allowed.

events = events.filter((e) => e.time > cutoff);

Why it matters: sliding windows give a precise, fair limit at any moment.