sliding-window-limiter

A JavaScript implementation of the Sliding Window rate limiting algorithm.

Features

• Sliding window rate limiting with configurable window size, unit, and slice width
• Pluggable persistence store (in-memory by default)
• Written in modern JavaScript, using lodash and luxon
• Thoroughly tested with Jest

Installation

npm install sliding-window-limiter

Usage

const { RateLimiter } = require('sliding-window-limiter');

const limiter = new RateLimiter({
  name: 'api-rate-limit',
  max: 100,                 // max requests per window
  window: {
    unit: 'minute',         // time unit for window
    size: 10,               // number of slices in window
    width: 1,               // width of each slice
  },
  store: customStore,       // optional: provide your own store
});

// To check and update the rate limit:
const allowed = await limiter.update(1, new Date());
if (!allowed) {
  // Rate limit exceeded
}

API

RateLimiter

Constructor

new RateLimiter(config)

• config.name (string): Unique name for the limiter
• config.max (number): Maximum allowed value in the window
• config.window (object): Window configuration
  • unit (string): Time unit (second, minute, hour, etc.)
  • size (number): Number of slices in the window
  • width (number): Width of each slice
• config.store (object): Store for persistence (must implement get and set)

Methods

• static async RateLimiter.load(config): Loads a limiter and its state from the store
• async update(value, timestamp): Attempts to add value at timestamp. Returns true if allowed, false if limit exceeded.
• set(state): Sets the internal window state
• valueOf(): Returns the current sum of the window

Window

• Internal class for managing the sliding window logic

Testing

Run all tests with:

npm test

License

ISC

Author

Dima Michaelov